Quite honestly it's absolutely ridiculous to expect each chat channel to remain 100% true to its name. A large part of the time is people casually chatting to each other which in no way detracts from the "true" nature of the channel. I can't count how many times I've seen off topic exchanges in market and new player chat. It's never been a problem untilpeople, who have a legitimate use for that channel, get ignored which I have not seen happen. If it does happen, then I do support intervention by the GMs.
Maybe I'm off base here not having all the information but I strongly believe chat channels should be used for chat whether or not it follows the intent of the channel. It makes the game more interesting, dynamic and entertaining for the vast majority of players.