This technique was used in Runescape commonly..I'm sure it will work on World of Warcraft as well, at least on the noobs.
Basic layout:
You and your partner are going to scam a sucker using WTS and WTB scammage.
1st step: Find an uncommon item and say in trade channel: WTS (item link) 1000g (or some other high number) (and of course this should be a rediculous price for the item)
2nd Step: Have your partner whisper around and ask random level 70's that have recently said things in trade channel: Hey, were you selling the (item link)? I'm willing to pay 1300g (or some number near the previously stated cost)
3rd Step: If the sucker/noob has fallen for this, (partner one) sell him the item for he will likely find and whisper you in order to make some cash, then partner 2 will whisper him saying his previous whisper had a typo in it and he meant 130g instead of 1300 or (minus a digit from previously mentioned price)
Warning: Try to use a chat outside of WoW itself, such as vent, chat logging can come back to haunt you

Also, make sure there is no association between you and your partner during the scam..people are becoming hard to scam these days.
Often players will see the scam and refer you to your partner, in which case I'd suggest meeting up with him and staging a trade
Enjoy, this can work well on the right people