One was also the worst GM I have ever encountered, basically his games were about him proving how much more intelligent and important he was over everyone else. His games were railroads where every encounter was something impossible and where the characters were not allowed to use their powers. He'd set puzzles which made no logical sense and were impossible to complete (except that one time we guessed right, and then he changed the answer). Basically it boiled down to sitting there for 20 minutes until he decided that we passed the puzzle. As a player he always played a 'lawful good' character who is never good and hardly ever lawful. Despite boasting of how he played longer than the rest of us, he never got the spells correct, they always did more damage than the rules suggested. We advised him the correct damage, at first until it became clear he knew but didn't care. The GM eventually just ignored the claimed damage and went with what the rules said. At the time he was our boss and the games being run after work. For a while it was one of those things where we had to play, or he would become difficult during work hours.
The other one was not deliberately difficult. He was the cousin of a man locally called Honest John, since his name was John and he was definitely not honest. The cousin was not the smartest cookie in the box, also he had a temper when he thought people were pointing out he wasn't the smartest cookie in the box. In one solo game his character went into a room, pulled a lever fell into a trap had to fight monsters till he managed to get back to the original room, where he then pulled the same lever. He did this about five times, never realising that he was activating the same trap over and over again. In the group game, the characters found themselves dangling by a rope off a cliff. For no apparent reason he cut the rope....above him, so he and everyone below him fell off the cliff. Later he began to add things to game narrative, not things his character was doing but story elements, which he expected the rest of us to interact with. This culminated with him discovering a stuffed snake (which the GM did include), which then tried to attack him and then started talking to him, worryingly suggesting he murder all the other characters (which the GM did not include, it was just a stuffed snake just a bit of scenery). We found reasons not to include the cousin after that, especially when he got arrested for assault a few weeks later.
