I have found a new pet peeve.
I hate scientists who hear about work second- or third-hand, and dismiss it without having seen it.
The ones I particularly hate are good at coming up with realistic-sounding technical arguments for why it must be wrong.
Without considering that, not having seen the work, they don't know which controls have been done and which haven't. It somehow never occurs to them that those issues might have already been addressed.
I also hate the ones who, when asking questions of any kind, always manage to make them sound like royalty addressing the lowest, slave. It's like they wear a neon sign that says, My IQ is bigger than yours!
When, from the content of their questions, it clearly isn't.
Oddly, I don't know any women who do this. This isn't to say they don't exist. But even the women I know who ask withering, incisive questions don't do it in this type of condescending tone.
In fact, I never met anyone who did this until relatively recently, and the two I'm thinking of right now are a grad student and an unrelated young PI.
I wish I knew a fitting way to get back at them for things they've said to my friends or about my friends' work. It just infuriates me that they would be so arrogant, and that they don't realize that unless you've done similar experiments yourself, you probably don't know what you're talking about.