This happened to my guild last night, and I thought it was hilarious tbh.
Going to break it into some short steps to see if its more understandable.
THIS IS A LONG SCAM, DO NOT DO IF YOU HAVE NO PATIENCE.
Step one: This is the most lengthy part, ask in high level guilds, that are raiding BT and Hyjal, guilds where the members will have a lot of money. Second, ask all of their members if there is a character that they have wanted for a long time, if there is, say you will level it and be payed X amount of gold for it. The more gear you get him, the more he will be willing to pay in most cases. Once the agreement is made, start leveling. Keep contact with the buyer, as to gain their trust. (In my guilds case, our member payed a guy 4000g for a S1-2 warrior.)
Step two: Alright, its been about 2 months depending on the speed you level at, you have geared the character up. All this time you have becoming good friends with the buyer. You arrange the sale, receive the money, hand over the account information and then leave it at that for about another month.
Step three: He is completely unaware what is about to happen if you have kept a good friendly relationship with him. Check the server forums to see what nights his guild raids on, ours was an off night TK raid last night. During the raid, recover the password, get on the character, and get to the bank. Grab whatever you can but do not say ANYTHING. Do not do anything, do not leave the guild, do not whisper anyone. Things will seem as if the buyer has done it. Early into the morning when few are on, and those that ARE on are AFK in AV, so nobody will notice, leave the guild and change your name or server+name. Log out, remake a character with the same name and race, and level him to about 6-7. (Take any other working precautions you know.)
Step four: Obviously after awhile they will notice it is gone, so later you will most likely be reported. As long as blizzard doesn't look too deep into it they will see a 6-7 warrior who has had no affiliations with the guild that has been scammed. If they do look into it, obviously your pretty screwed. This scam is really only worth it if the guild is well progressed, has a good bank, and you can level fast. Depending on what they want the payout can be big, like ~7000g, or smaller like 3000g. Either way, if you can level fast this is a great scam.
To sum it up,
1. level a char for someone
2. sell it
3. take it back once its in a good guild
4. take the bank
5. change names
6. level another with the exact same name
7. profit!
If there is anything to be added, please post it, or if this or a similar scam has been posted before, please provide a link.