I think that there's a big difference between close-minded, opinionated, and particular. I, personally, am particular. This means that something has to be well more than mediocre for me to bother listening to it more than once or twice (or course, there's a lot of subjectivity involved in any such qualification). At the same time, I'm also not inclined to listen to music I don't find entertaining, regardless of its quality.

So, I don't listen to Eminem because I largely don't like the mainstream rap ideals (I realize that Eminem is far from mainstream in his lyrics and delivery, but much of the rest of it is quite so, to me). But I don't listen to Britney, 'N Sync, and Limp Bizkit because I don't enjoy that sort of bubblegum pop or nu-metal (which isn't far away from bubblegum pop, in my mind) in addition to the fact that they're crap.