Just played in some japenese ctf sever and there was this guy(name removed) in spectator mode. The peculiar thing is this, even though he is not supposed to manipulate the game outcome at all, he runs around (invisably, of course, since you are not supposed to see spectators becuase they are ghosts or whatever) killing playes from both teams!!! And too top it all, he uses teleport hack to 'capture the flag' or just keep the flag out of play. Personally, this was the most irritating hack ive ever experienced, you cant do anything(cept leave), voting doesnt help.
If you see someone(in the kill console) with a score of "-1", then its a spectator killing someone.
So I thought it must be really simple, spectator scoreing in any way should be auto kicked immediatly, sort of like the mechanisms in place to kick cheaters based on logic (you cant have rambo bow in a death match).