I find it annoying when people keep trying to make me watch the subs of an anime before the official dub (if there is one), as it causes (at least in me) expectations for what the characters should sound like (even though looking at their and reading the manga does the same, but the vocal expectations I get from reading manga tend to be spot-on as opposed to basing it on their Japanese voices).
Also, I hate Homestuck, Attack on Titan, and a couple of other series simply because some overzealous fans won't shut the [tornado fang] up about it and keep trying to cram it down my throat (it's a reflex brought on by stupid people trying to enforce their opinion on me when I don't give two shits).