I played World of Warcraft for two-and-a-half years without falling for any of the numerous scams around. No longer, now I'm 125 gold poorer, and one experience richer. I thought I'd buy a [Recipe: Flask of Distilled Wisdom] really cheap, but got sold a [Recipe: Flask of Distilled Wisdom] instead. You don't see the difference? Neither did I! The one I wanted is the recipe that has been in the game since the beginning, with a 2% drop rate from the end-boss of Stratholme, living side. The one I bought is the new version, which you can buy and use only if you are exalted with the Cenarion Expedition. Due to slopply game design from Blizzard this recipe isn't bind on pickup, so once somebody is exalted, he can buy these recipes in endless supply for 4 gold, and scam people into believing they are the real thing, selling them for hundreds of gold.
And I can't even report the guy who scammed me, although I remember his name. There is nothing in the Terms of Service or EULA stating that you can't sell worthless crap for large amounts of gold. It's caveat emptor, buyer beware.