I would have to agree with Mr. Fournier. While not an actual "bug" per se, they do make maps unworkable for other players, thus preventing the completion of quests that require killing x number of certain mobs or acquiring item y from mob z because every channel has a blaze wizard on every area in Mu Lung and Signapore CBD.
I would also like to point out that I have been occasionally disconnected while crossing areas infested by hackers and getting the message that I WAS THE ONE using an illegal hacking program!