A recent patch introduced a right-click "report as spam" message for yells, says, tells, etc. Unfortunately (?) the option was not enabled for party chat. So gold-sellers are now trying to spam people to join their groups as it's the only way they can deliver the URL* and not be reported. Enjoy the loophole while you can, guys!
* If you don't count corpse-body letters dropped outside the gates of Ironforge.
