What annoys me the most about this sort of thing is when someone asks you what music you listen to. The fact is I listen to a wide variety of different genres, and I find it hard to pigeon hole my taste in music, which is basically what the person is asking you to do (or at least thats thats what always seems to happen). Because I play guitar and do music technology at college I work with a lot of musicians and people involved in the music industry and that seems to be a question I always get asked. However, most of the time they're like me, they listen to a lot of different stuff.
I remember once when I was assisting the music department when some kids from secondary school came in to our college for a taster day. Some of them asked me what music I liked, so I replied as I always do. They then went on to ask who my favourite band was and when I replied with Muse they then jumped to the conclusion I was "Mainstream and liked Twilight". Those little fuckers... I've loved Muse ever since I first heard them back when I was 11 and they have been my favourite band for a long time. Just because they have a few songs that are in twilight and are now much more popular and well known then they were 6 years ago doesn't mean anything.
The point I'm trying to make is stereotyping will always be an inacurate way of understanding an individual because although people always have interests in common, everyone also have their own individual tastes that others may not understand or agree with, so they stereotype them.