I don't own a horse but I'll join in anyways!
Skippy (current lease horse): Spooky! Girth sour and has thwarted all of my attempts to cure it. He has gotten a bit better, though.
Lucky: Hot. Girth sour. Didn't stand well to be groomed.
Diamond: Would try to rip the reins our of your hands. Really loved trying to wander into the middle of the arena. Very hard to get going.
Circe: One second she would be sweet and the next she'd be trying to take a chunk out of you. I never could figure that horse out but for some reason a lot of people loved us together. And her trot...so Western, but in an annoying way! (No offense to Western people, her trot was magnificent for sitting, but for posting...argh! Made me want to tear my hair out).
Those are just a few that I ride/rode frequently.
And of course, horses with bad manners always make me irritated! Especially:
*The horses who you have to form a strategy to be able to lead them. You know the ones. "Oh, I'll just circle!" You say....sometimes it works out...others...
*Horses that try to eat while I'm leading them (with bridle on) or riding them.