For me, it is when they make guys look like freaking chicks and I can never tell which one they are. This goes for Haku from Naruto and some guy from Sengoku Basara whose name I forgot.
EDIT: Also, chicks with extremely oversized breasts.
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Androgynous characters... Sexual fan service... Filler flashback episodes (Where the flashback is events you have already seen, not someone's past)