A possible way to kill RMT sellers in chat..

[SamSmoot]

The current system of just kicking the spamming character does nothing. A replacement comes online in minutes with the exact same message. SE needs to attack the message itself.

After a certain number of reports for posts with message content that's say, 80% the same or greater, start by flagging the site URL. Any further messages with the flagged text in it gets blocked to prevent anyone but the poster from seeing the message (so they keep posting blind.)
They'll have to keep changing their URL every time they get blocked.

If they find a way around that, flag 10 random characters in the message, and block of more than 8 of them appear, so they'll have to change the whole ad every time it gets silenced.

Also, like in WoW, if you report chat spam, you stop seeing it for the remainder of your login session, so you get some immediate benefit from reporting.