Is there something in fic that really, really bothers you when you read it? The sort of thing that can turn you off reading, even if the rest of the fic is brilliant? Label it here... then tag five others to do the same!
Yes, there is!
I actually find it really difficult when people write the dialect of characters with a pronounced accent, because it invariably reads nothing like how the characters sound to me. Contractions are okay, the very occasional missing letter or couple of letters are fine, but when there's things like every g or h missing, or constant 'yer' or 'summat's, I'm left blinking at the screen in confusion. I just --- I find it so hard to concentrate when I have to parse what I'm reading with what I hear. I much prefer it when someone says the innocuous, "he spoke with a cockney accent", and then, because I know what a cockney accent sounds like, I read the words the way a cockney accent sounds to me. No pausing to see if I've got the gist. No frowning, trying to see if I can hear a particular character say a word. I can read with little distraction.
Okay, I'm not tagging specific people, but have at it...