No matter what you do...
Someone will always try and game it. The thing that Blizzard (Warcraft's makers) have always tried to do is block sellers of gold. You use gold in the game to buy better gear. This is not allowed by Blizzard under the terms of service, but it's something people do anyway.
So people spam you in Blizzard trying to get you to spend your hard earned dollars on getting gold from them. It used to be people would spam you in chat, blocked. They would shout alot, blocked. They would do trades with you, blocked. And so on. Then the other day I saw this:
Brilliant. Make about 50 characters, then get them all to fall asleep in a way that spells out the name of the domain you are trying to get people to buy gold from. The only flaw is that other people were lying on the Y to obscure it, but full marks for effort. And yes, that's my character at the bottom named after the one and only text editor.