I cannot say for high level PVP, but for the lower level matches (12-35), there is a player with multiple characters who joins a match and never accept when ready to go to battle. He also joins one char on each side and takes turns not accepting to go to battle, thus further delaying match wait times.
He only stays on for an hour or so and becomes a pest for other players.
Some of the names of his Characters:
Flint Wildcaster Paul Anthony Fist etc.
I have complained to KI about this before with no positive action. I know this is a difficult thing to Police, but it is frustrating an already dying PVP community.