regarding AF being to expensive... well, if the people have the money, let them buy what they want. usually, the person is working, or has rich parents so he has option of shopping wherever he/she wants. however, if money becomes a factor, then it's obviously a problem and either the parents or the buyer needs to not spend as much.
in terms of appearance, it's all about taste, as many other people have said. the only gripe i have, is that people buy these clothes in order to fit in or look like their friends. they should express their individuality instead of conforming.
personally, i don't shop at af or american eagle, but i do stop by and check them out every once in a while when they have good deals. i mostly shop at kohls, target, and jcpenney, where pants are usually under $20 and shirts under $15. i have better things to spend my money on, and in MY OPINION, most of their stuff is crap or not worth the money. there's my 2 cents.