I've gotta say, we all are different and all have our own pet peeves. I took a test the other day on what mine would be and I was slightly surprised. The worst for me has gotta be working for someone who gets bent out of shape over a question. Now this may seem specific, but based on my previous experience, this happens to be way more common than you would think.
I am a very independent person and I rarely ask questions, so when I do ask one, if my boss sighs or gives me attitude, truthfully, I get pissed off.
I've had employers in the past who were great, and every once in a while it happened from stress, so I never took it personally. But if EVERYTIME I ask something small I get an "ugh" or an eye roll, it makes me start looking elsewhere ASAP. I get we all handle our stress in different ways but to me that is just minimizing the importance of your employee's learning process. It makes sense to act this way when you're stressed out, but if you make your employees feel stupid or like a burden it! will! come! back! to! you!
What about you?