Rosetta Stone inconsistency with using articles before nouns.

Question

In a Rosetta Stone lesson, I noticed an inconsistency with the use of "el" before a noun. I know that sometimes articles are omitted before nouns in Spanish, and sometimes they not omitted. I remember one rule regarding whether or not the articles should be used, and that is whether or not the noun coming after the article is modified by an adjective. If there is an adjective modifying the noun, then an article ( el, la, los, las, un, una, unos, unas) is placed before the noun. If no adjective appears after the noun, then no article is placed before the noun. This is my understanding of the rule regarding this issue. Please correct my understanding of this rule if it is incorrect, or add more explanation if you feel I have not explained it adequately.

Ok, the two sentences in the Rosetta Stone lesson which piqued my curiosity regarding this rule follow: (1) Este hombre joven tiene el pelo azul. (2) Esta mujer joven tiene pelo negro.

The only difference in these two sentences that might be of consequence is that blue hair does not occur naturally. So maybe the "el" occurs in that sentence because the hair has been dyed. Am I on the right track here?

The other reason I could understand would be similar to English comparing and identifying two people. i.e. The man with the blue hair vs the man with the blond hair. There, the definite article sounds right. I want to hear what the natives say too. - rogspax, Jan 27, 2013

The first one sounds less natural to me, but if I was forced to hazard a guess, I'd make the same one as you did (though even then, I'd have expected un in place of el). - rogspax, Jan 27, 2013

Answer 1

Right now, he has blue hair. He may not have blue hair tomorrow. We're talking about the hair.
She is a person with black hair. Her black hair is one of her attributes, we're talking about 'her', not 'the hair'.

I'm sorry I don't know 'the rules', but if I heard these sentences in a conversation, this is the way I'd understand them.