I read it all, and it's more the writing style and the story line that gets me and keeps me. I can't tell you how many stories I've started to read that I've had to stop and rinse my brain out because they were so bad (grammar and rehashed trash really). I try as hard as I can to keep my characters cannon, and if I can't for some reason or another I make sure I explain it in an author's note.
I really could care less if it's yuri , yoai or het as long as it's well written and the characters are acting realisticly. I need a good story line to go along with the smut. There are several authors on AFF that I have read that can do that really well (Iggy, Squallfan, DB2020 just to name three), and nothing inspires me more than reading something that makes me loose myself in the story and cry when it's over.
It's what I try to put into my fics - realistic situations, love (or lust depending on the character), angst, completely evil vilians and just a touch of the soap opera ingredient to make it smarmy.