Agreed, it's only cool to like unpopular bands. Once the masses like them they 'suck', 'sold out', etc. However we've had this discussion before and nothing ever comes of it. I'm not going to lie, I sometimes just listening to music that is just fluff. It tends to be catchy, alot of people know of them, etc. Depends on my mood.
By purposely avoiding music that's popular, or that 'whiny 12 year old emo kids' listen to, you're just as bad as them. Listen to whatever the hell you like, regardless of what other people think.