jerks can slow you down drastically. worked with someone who was a genius, but couldnt move in a direction until he proved everyone wrong. it felt like every decision took hours to move on. even low impact ones.
I think most of us have been interviewed by such people. You know, the ones who grill you endlessly with obscure trivia trying to find that gotcha that proves they're smarter than the candidate, at which point I'm begging to be rejected because I don't want to work with such people.