[ItsAlive75]

Well, I always saw the goth stereotype as a group of teens and preteens who are usually unhappy with their family or social situation, and instead of trying to find a way to break themselves out of their depression they choose a lifestyle that lets them wallow in it. Obviously, it's easier to accept depression and build yourself around that than to be proactive and improve yourself. So they wear black clothes and listen to music about death and are usually pretty nasty to anyone who is (or at least seems to be) happy with themselves. Once again, this is just my interpretation of the stereotype.

As for all cultural groups, it's just an easier way for everyone to make outside impressions on others without having to actually talk to him or her. It's like a TV guide; you don't need to watch the show to know what it's about, you have a quick summary of it and a label of what kind of show it is (drama, comedy, etc.)