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...