In a year I've flown with one guy who yelled at rampers, berated gate agents & F/As, argued with ATC over runway assignments, and refused to start the second engine until exactly 2:00 before takeoff (on an 88) despite having a new FO struggling to get all the checklists done in that time. He's pretty much the only guy I've flown with who just failed at life, everyone else has been pretty fantastic (ok, there was the one 9/11 truther, but he was at least a nice guy).