It could be worse I guess, they could just pos-hack their dead bodies to spell out their seller site name. That was a thing in WoW for a few months, where all you needed was a chat add-on to filter out the gold spam.

I guess what I'm trying to say is that RMT will do anything remotely, stupidly, and illegally possible to advertise to you, so just keep recording names and fill out the manual report, and hope 3.5 cross-server stuff doesn't leave huge loopholes for them to exploit.