certain extreme-fringe left-wingers, including advocates of violent political/social change, hard-line communists, terrorist-apologists, America-haters, kooks, crackpots, LaRouchies, and the like.
I don't know that I've ever seen a communist, terrorist-apologist, America-hater, leftist kook or crackpot tombstoned at DU, and certainly never as quickly as they tombstone anyone to the right of, well, them. However, given the nature of their TOS, we should do them a favor and identify the communista, terrorist-apologista, America-hatera, leftist kooka and crackpots for them so that they can proceed with the general housecleaning. For example, Underground Panther, who considers herself a cat, is clearly a kook. Anyone who makes excuses for flag-burning at OWS events can explain why they aren't America-haters.
Who's up for compiling the list?