I don't know about idiots but people that irritated me. OK, yes they were idiots. One was a know it all with his son, very young boy. He never helped him just scolded him for making dad look bad. Dad was a tech diver and not like the rest of us so he almost couldn't be bothered with even his son's questions. On one particular dive he even got separated from his son who came up with another group. Dad stayed down twenty minutes past the given bottom time and made the dm's go in and find him. The second couple I will call the "bicker's". They lived in a northern state and didn't see the sun much, nor the water after seeing their skill level. The wife seemed to hate the husband and he thought she couldn't tie her shoe properly. So, they fought about everything. I have never wanted to turn off some one's air more than I did that day. The only time they weren't yelling back and forth was under water but they did know quite a bit of single finger sign language. The wife was a little on the big side, quite nervous about diving in the first place. She had lead everywhere to help her not float in odd angles however, she didn't need that lead very often as she struggled to equalize on every dive. I had finished a dive and they were still on the surface trying to get under and he could be heard three hundred yards away just screaming at her for being "so stupid".
I am kind of afraid that if I ever do get on a dive boat and there are no idiots that I notice, then it might be me.