The first is British bleed into American settings, that just throws me right out of the story. One minute it's all good, and then a snigger or have a go or for f**k's sake or wonky or the like pops up, and then more start piling in and that's it— the story's ruined for me. *cries* I know not everyone is bothered by this, but to me it's like someone singing off-key (which is intolerable when you're pitch-sensitive, believe me). I've thought many times about creating a 'helper' page for equivalent British=>American phrasing or "things to avoid", because I see this in both of my main fandoms, but I haven't found the time yet.
That said, I have similar thoughts about a quick-and-dirty summary for writers of all origins regarding how to format dialogue, or the whole lay/lie distinction and how to tell what tense you're in and the red flag words that belong with one tense but not the other (can/could, may/might, will/would— you get the idea). Potentially helpful! But where is the time?
The second area, which is probably an even more personal issue than the first, is AUs and ensuing characterization. I'm not all that big on AUs in general, though an author with the right touch can persuade me very easily— this has proved especially true for J2 RPS, which is the only RPS I read. It's got its own set of rules for me, apparently! But when an AU tends to work for me in general, in ALL fandoms and settings, is when I can still very clearly see the original characters despite the AU circumstances and setting. So I ran into a surprise last week in reading a J2 story that most people absolutely love. One of the characters was a stereotypical shopoholic fashion-and-grooming-obsessed semi-prissy gay man. And while the story was incredibly well-written, I just couldn't get past that. It didn't feel like I was reading J-squared, it felt like I was reading a story about some totally different people wearing Jensen's and Jared's skin suits. And that really has no appeal to me— I quit half way through, because I just couldn't maintain any interest in the story. I've run into some exceptions, where the character leans in that direction but still has enough Jensen or Jared characteristics to hold my attention. And there's one in particular that was a retelling of "Clueless" where it was totally not a problem for me (Hi, Sonia!). But in general... the appeal of J-squared for me is Jensen and Jared, together, and when one or both of them is 'off,' then it's no longer my idea of J-squared. *is picky* *envies readers who aren't bothered by that*
Actual dreck: Sure, there's badfic out there, but fanfic has some incredible writers in every fandom. And there are times when what people write for free on the Interwebs SO easily exceeds some of the things I find in published books that it boggles my mind. Cases in point:
Wow, look— I totally avoided slamming Jonathan Kellerman and his "Mary Sue" mysteries involving Alex Delaware! Oh, wait. Um...