I intensely dislike both people who continually bash a band, and those who see no fault in a band, and how both seem to think that anyone who disagrees is a loser, poser, and so on.
I also dislike people who pseudo-religiously follow a band, until they make it big, then they are instantly "sellouts" and anyone who discovers them then as opposed to when they were pretty underground is a "poser".
What's happening here, people? To me, music is art, and art is pretty subjective. People aren't any less worthy of respect just because they like something you hate, or vice-versa.
And as for bands "selling out"; what proof is there that they did? Are there people stalking them? Living with them 24/7, heck, living in their HEADS so they'd know that they're total sellouts? We can't say that they didn't sell out, but then again, neither can we say they did.
Summary; these arguments and flame-wars are pretty damn immature, which is why I actually HATE to get into discussions concerning music. As the question states: give a reason why you hate the band (and, yes, not liking the sound is a valid reason), instead of the usual drivel. And I say, please be mature about it.
To answer your question. I neither like nor hate MCR, though I do find a couple of their songs amusing (yes, amusing). Then again, my taste in music shifts with my mood, and my "favorite band" changes on a weekly basis. Who knows what my thoughts on MCR might be in a few days.
Edit: Oh my GOD, Know?, don't get me starting on those fangirls.... ugh....