To tú or not to tú...
I have read all previous posts regarding the usage of tu and usted.
Clearly it is not as simple as a difference in familiarity, respect nor relative position determining whether tú or usted be used. It is also apparent that the use of usted and tú varies between cultures and subcultures.
Would native speakers take the time to offer their understanding or their usage of tú and usted, as well as specifiying exactly where they are from, their social background and any other factors that would help a non-native speaker try to get to grips with this ambiguous beast.
As a starter for 10:
I live in Bogotá.
My girlfriend, from a lower middle class background, uses usted when talking to her brother, her explanation being that they were not that close when growing up.
My male business partners, although good friends, tend to use usted. My girlfriend's explanation for this is that it would simply be gay, in the homosexual sense of the word, for these guys to tutear amongst themselves. The irony here is that marica is used in Bogotá as might be pal, mate, buddy, dude, bro etc. in many English speaking societies.
Another friend who tutears as you might expect with her friends, uses usted with her sister with whom she is very close. She tells me that this is out of the respect that she holds for her.
My girlfriend told me that it was, at one time, usual amongst the lower classes to only use usted as it was not know how to conjugate in the 2nd person plural familiar.
I've also been told that between people who normally tutear, using usted would signify annoyance, seriousness etc. Do other people switch between the use of tú and usted to signify different things? Would other native speakers understand the significance of someone addressing you with either tú or usted at different times?
It's a veritable minefield I tell you...
12 Answers
There are two factors involved in the use of tú vs. usted: regional use, and social custom.
For example, the Andean South American countries differ from most other Latin American countries in that they tend to use "usted" with friends and families - that's what you have observed in your Colombian environment.
Argentina is also odd, because it's the only conutry where "vos" is still used widely. Some other relatively small regions, such as Zulia, in Venezuela, also maintain the use of "vos".
In the rest of Latin America, and Spain, the basic rule stands: if the situation is informal, use "tú". Otherwise use "usted". Having said that, the tricky part of course is being able to gauge when a situation can be safely considered informal. This can be awkward even for native speakers.
As an example, I consider that SpanishDict is an informal environment, and that all other Spanish speakers in the Forum are my peers - regardless of seniority, age, or gender. So I personally address all of them as "tú", and expect to be addressed the same way by everyone. So far nobody appears to be taking offense. 
On the other hand, I have to speak with customer from different Latin American countries every week. Although there is a trend toward the informal in business communications, I can never tell whether a customer would feel more comfortable with the formal or the informal mode. So to be safe, I always start rather formally with "usted". If the customer switches to "tú"; I generally try it out to see if it sits well. Once or twice I have perceived that the other person did not appreciate my switch, even though they were still using "tú" when addressing me. So I continued addressing them as "usted".
The situation is about as clear cut as it is in the business world in the US, where the tendency seems to be to address people by their first name. I always start by addressing English speakers as Mr. or Ms. LastName, until or unless they switch to first name basis and /or ask to be called by their first name.
Sometimes, the Head Honcho of some big company in an expensive suit (say Mr. Richard Bigego) will address me by my first name. In those cases I always continue to address him (women don't seem to do this) as Mr. Bigego, never as Dick. In an analogous situation in Spanish, I'd continue to use "usted", even though he may address me as "tú".
Hopefully you're thoroughly confused by now. Else just ask me to repeat the whole thing, and I'll do my best to make it murkier! 
In Mexico is just like that... tú (informal), usted (formal)... and is used as you said, if it's someone I don't know... and older, I'd use usted, if it's someone I respect it's the same...
If it's someone I'm familiar with, or that I just met... but if it's about my same age I'd use "tú"...
The out of rule usage starts from Guatemala and down to South America... I've heard them addressing with "usted", all the time... and in many cases in which I'd use "tú"... so... there you have the demographic you need to ask...
Old thread or not here is my take from living in Mexico.
My girlfriend, a mexicana, uses Ud. with her mother, but not with her brothers and sisters. She uses Ud. with doctors and government officials but not with her friends.
I find that the government almost always uses tú when talking to the public in written form, signs, announcements, etc. and Uds. when speaking in the plural.
Businesses also use the tú form in advertising and announcements.
I've also been told that between people who normally tutear, using usted would signify annoyance, seriousness etc.
Not that this answers any of your queries (which others have), and I don't get to interact with any Spanish-speakers, so take my comment in that light...
But, to me, the above would be very similar to two close people (say a boyfriend and a girlfriend) having a disagreement. And suddenly they are saying (with coldness in their voice), "yes, SIR" and "yes, MA'AM" to each other...thus bringing a cold formality to what once was a warmer relationship.
I had often wondered if Spanish-speakers accomplished the same thing by switching from tú to usted. I guess they can and do.
Also, I'm from the Southern USA, and a little comparison might help. Here, among some parts of my family (dad's relatives), it is considered very rude for the children not to address their parents as sir and ma'am (my dad, thankfully, broke with that tradition). So, there are these little spots in our culture where sir and ma'am are used in situations where most would not (it can vary by family). Keep in mind, that I've never heard of brothers and sisters addressing each other as sir or ma'am (except in cold sarcastic tones as mentioned above...usually when one or the other has acted like the boss of the other or when one has suddenly acted to formally to the other), but it would certainly be possible in certain family cultures.
Of course, I cannot comment with any depth on the whole usted - tu thing except to say that it was confusing to me until I realized that (as a general rule) I could use usted with people I would normally address as sir or ma'am and tu with everyone else (not that that would work where you are).
Apparently there can be some added regional depth to the whole issue...which I likely will never be in a position to encounter.
Cheers.
This is interesting, and I think one of those things you just have to start of with a simple model of in your head, and then tweak over time. I don´t think you can hope to learn every scenario ahead of time, nor avoid all mistakes, or compare across various languages.
I do remember being surprised by my very good friend´s Colombian wife. She had been traveling a lot, and so after I started learning Spanish, I didn´t see for for 6 or 8 months. I was indeed surprised to hear her use usted with me, not yet having heard Colombia was an exception to the sort of baseline usted-tú assumptions. And I knew her and the family well, having been in their wedding party. But she explained it was a sign of respect, and she used it even with close family. I´ve only heard her say tú with her daughter and husband. I don´t think because there is any less respect, but rather than all ceremony is tossed aside.
Otoh, another good Colombian friend and I only use tú. We´re about the same age, and maybe also playing a role, is that he´s a very left leaning artist, and ultra egalitarian. Not quite a communist, but not one who pays inherent respect, or much cares for class and title. Makes sense given his beliefs, despite him being Colombian.
This is a darn complex and nuanced topic, that much is for sure.
Buena suerte.
When I use usted the implication is we're not friends, family, peers, or equals. Whether or not I think you are my superior I will speak to you with elaborate courtesy. We're doing business, nothing more. I will call you Señor, Señorita, Señora, together with your last name.
When I use tú, it's the opposite. We're friends, colleagues, siblings, cousins, peers. We're at a party, or watching a sporting event. We use first names, or some rude nickname. We get drunk together. We pester each other with stupid text messages. Somos familia.
I know it's not usually this black & white, but for my job I have to speak with Spanish-speakers from all over the world and it's much more efficient to standardize my speech and err on the side of formality. I have to admit that I can't stand it when the people I speak to for work get too familiar with me and ask me personal questions. Of course I don't say anything, but in my mind it's, "como si fueramos amigos".
This isn't exactly the "tú" - "Usted" question, but I couldn't find a better place to ask.
In English, the word "you" is often used in an impersonal sense meaning people in general, and not anyone specific. As an example, in giving directions, one would hear, " You take a left at the first intersection, then you go 3 blocks."
Does Spanish ever do this as a substitute for the impersonal "se" construction?
My own training tells me I should say, "Se paga la entrada al museo aquí." But I heard recently a Bogotano say, "La entrada pagas, no es gratuito." This in reference to visiting the Salt Cathedral.
It struck me as unusual that one should pay to enter a cathedral, even though a tourist attraction, and also unusual that I should hear "pagas" in this instance.
Any native insight would be greatly appreciated.
edited
From what I've experienced it is always best to "usted " until asked to "tutear".Especially as a new learner of the language.This has been covered well,I'll only add ,in my opinion is this.It is black and white,I like gringojrf's answer.
Well... I am definitely not a native Spanish speaker, but I find the tú/usted conundrum interesting and somewhat perplexing as well, so I'd like to toss my two bits in. I just read the short story "No oyes ladrar los perros" by Juan Rulfo, a Mexican writer. Most of the story is taken up by a father speaking with his son. Basically, the son is hurt and the father is trying to carry him to a small town where the son can get medical help. On the way, the father berates the son for all the awful things he has done. When the father is asking the son if he sees any signs of a town or hears any dogs barking, he addresses his son as "tú." When he is yelling at his son for letting his mother down and running with a bad crowd and killing people, he uses "usted." He keeps flipping back and forth between the two throughout the story, which takes place over the span of maybe half an hour. This would back up what people have been saying about using usted to indicate annoyance, I suppose. By the way, if anyone happens to read this and notices something wrong with my summary of the story, please feel free to point it out.
You'll have to check with people from Colombia, I'm afraid. I can tell you that in Spain "tú" is informal, and "usted" is as formal as using "sir" and "madam".
I use usted just out of respect, I think that is a perfect way to show your education and your good manners, however, I have some friends that think that saying tú is a way to show self-confidence and attitude, I don´t believe so because you can be educated and at the same time impose your attitude.
So, I use it for education with older people or with poeople that I don't know. I am from México city from a high-middle class.
