I can't help but feel uncomfortable whenever someone role-plays a canon character, regardless of whether they're a good role-player. Even if that character is a prominent character in a long running series, there's still the extremely high chance that they'll get something completely wrong about that character, and that their emotions and personality will influence that character.

I also get annoyed whenever people use a story they like and try to emulate the intense parts of it whilst disregarding the pacing that made them good in the first place, bonus points if the original story doesn't have good pacing either.