This scam is really neat.. It's not much of a scam, as much as it is a way to get someone banned that annoys you. (I.E; Spammers in trade chat).
Ok, well, in this scam, you have to first have a target, or someone annoying. Walk up to them, open trade, without saying a word, and give them 200 gold, or a big amount. Wait for them to hit trade first, then you hit trade. Now, immediately report them for scamming you with the trade-window scam. When the GM arrives, talk like a normal teenager (Don't use all caps, maybe shorten 'you' to 'u', etc.), and say you were scammed. Whenever blizz checks the logs, it will look exactly like they did the trade window scam. This especially works well if you have trade chat spammers. Just get atlasloot and say "WTS [Warglaive of Azzinoth]" or something, and if you can get the spammer to say "WTS [insert epic or legendary here]", It will look even better.
Or, to scam their account, first know their E-mail. Check on various WoW-related websites to get it. After finiding it, do the exact same you just did, except don't report them, and send a fraud message to their E-mail saying "Several Players have reported you scamming... etc. etc. " from one of the many posted websites that let you send like your from a different E-mail. You know the drill; sound official in the E-mail, etc.
But, of course, I haven't tried this yet, so I don't know if it works or not. It'd probably be good for one of you people with no gold troubles to try, .
Happy Scamming!