I don't really avoid it tbh. I often happen to like things that are not mainstream but every now and then it happens anyway.
One thing I've always actively refused though is watching Last Samurai. Will never EVER watch it if I can avoid it.
Like RyRy, I like whatever I like, mainstream or not. I try not to limit myself to anything that trivial but I just so happen to have more non-mainstream things that I like than mainstream. (Mostly in regards to music).
Yeah, music is a taste thing but I do really like artists who cross boundaries and utilize music like it should be utilized. The different categories in rock move me more than usual lovey-dovey subgenres.
But for anything that is experimental, I'm more for it. Mainstream items stay in the limelight of what the majority is used to. It can get dull, so cheers to those who keep variety alive. Vive la revolucion!
Mainstream is the root of all evil I say the less people know about it, the more I like it. It gives me that feeling of being on the inside. Also, mainstream doesn't care about music about life or truth. They care about repetitiveness about sex and getting drunk. Who wants that?
Also, before Owl City wrote Fireflies and got on the mainstream, I was such a fan of him and I knew lots of cool details about him, but now that he's famous I sort of don't want anything to do with him. It just made me lose total interest. Same thing with the Twilight Saga too.
Now, with Harry Potter, that's different. Harry Potter is about friendship, love, and doing what is right in the face of adversity. Harry Potter deserves its fame and merchandise at Hot Topic.
Twilight is about how important it is to have a boyfriend T_T
I guess my point is, I like it if it is genuinely worth liking, and the less other people know about it, the better.