(This does not apply to something I'm beta'ing, just so you know! This is the ostensibly "finished" fic!)
-Weird Formatting. If you have not yet learned that "smart" quotes are anything BUT that, and that they make the Yahoo! engines go buggo, you haven't been posting long enough. I'll take another look when you figure it out, really I will.
-Lack of Undisputedly Needed Commas. I MAY keep reading if I see, "Don't touch that you idiot!" I will NOT if I see "I do not think you completely understand Professor."
-Harry/Draco Cute-Fests, unless there is Shagging. The sad thing is that many of these are really GOOD, but there are just so MANY of them. If the "Harry thinks Draco has too many pairs of socks, and tells him so, but Draco doesn't listen" fic does not at LEAST have a decent handjob in there somewhere, I can't spend the time. I want the lurid details, guys. (Harry/Ron Cute-Fests I will probably still tune in for just because they're so much rarer!)
-Any fic that contains the line, "'What is it, love?' said Snape." (Unless it's parody.)
-Any fic with (Part 6 of 35) ot (Part 24 of ?) in the headers. I can't do it, guys. Can't wait for big honkin' WIP's, or even choppy multi-parter completed fics. I'd rather scroll down three hundred pages than click "Next part" twenty times.
I'm sure I got a bunch of others, but that's all I can think of just now. Post yours here and we'll have a big commiserate-fest right here!