I already mentioned this in my introductory post 'cause I'm a derp, but it all boils down to two things that bother me more than anything else:

1. Lazy, derivative or just plain cop-out writing. I cannot bring myself to read something that's been done a hundred times already.
2. People who gush so much in their writing that it detracts from the writing itself or the character it's supposed to be about.

Now, I don't claim to be some kind of expert on writing, but I'd like to think I've been doing this long enough to have a relatively high level of skill at it.