Hmm, a chance to rant and whine? Count me in!
I hate spelling errors, homophones, and attempts to sound more formal in language that fail terribly.
I hate porn that defies the laws of physics and/or reason (twisting, unnaturally flexible for a lazy character, coming in gushing spurts in unison every time)
I hate "comedy" as a genre, because it seems to attract a lot of lazy idiots, and I'm just not prepared to wade through that much swill. (I love well written comedic scenes, though. Just haven't run across many yet.)
I hate that when things are crossed over, it's always handled poorly. I'm counting my own crossovers here too. >.<
I hate a lot of heterosexual romance fics because they lean more towards Americanisms (in dating conventions etc), and tend to either end in really unrealistic sex, or marriage and babies. (In fact, I hate some Yaoi/slashfics because of this too)
I hate Mpreg. I've never found it handled well, and there's NO reason the characters can't adopt or find a surrogate mother. None. I'd rather gender-bent than Mpreg.
I hate a lot of Yuri AND Yaoi romance fics because they seem to be written more by members of the opposite sex (respectively), and focus on visual rather than sensual aspects of sex. In non-sexually-explicit romances, I find they portray exaggerated female characteristics (both). Also, I dislike when everyone in the cast is suddenly gay. Really I hate the degradation of character that I associate with a lot of sexually themed fics. It is possible to do this well, people!
I also dislike the culture of hate that surrounds pairing choices in general. I used to keep my gay, lesbian and het fics separate and participated in communities under several handles merely because there seemed to be a lot of dislike and ostracism towards anyone who wrote in variable sexual orientations/pairings.
And what is up with all the freaking Yaoi!?
Don't even get me started.
It has put me off of a lot of forums, discussions and threads, people blaming a sexual orientation
label rather than the general low quality of writing online or a personal dislike/apathy towards GBLT or het romance for their reactions to any given fic. I'm not saying everyone should go out and read gay/lesbian/het fics when they dislike them. But I am saying that if "Yaoi" is shit, then it's all shit really, and singling out a particular sexual preference for vilification disgusts me. Surely we left that shit behind a decade or so ago.
Ah, and I've championed the cause of het/gen/yuri to friends who have made similar nasty comments about those IRL, so I'm not reacting only to the above quoted comments about Yaoi here, but to all gender-preference bashing that I've encountered.