I've noticed that alot of people here complain after they lose access to an account that they scammed, or someone recalling the money they payed them for the scammed character. I have a method that almost 100% of the time avoids that, and I always keep what I have taken.
After you gain access to the account, make sure you have full info, yada yada. Get on the account, check it out, what does it have? What level is it? Any vanity items? After you made your toon "appraisal" get ready to make a post on an accounts selling website.
What you are going to want to look for is a trade, find someone who wants the toon you have. Either make a post, or lurk a bit, it's really your choice. After finding your person, contact him on his preferred messenger, and begin the trade. Make sure somehow during this trade process you find out what email he is using on the account, or what email he is using period. (Don't forget to recall the account you are trading him, since you haven't done so before this step. Try and do it from the web page just before the trade)
After you do the trade, send him a phishing email claiming that he has broken the ToS, and possibly send him other Keyloggers. You're not trying to get his info again, you already have it. What you're trying to do is make it seem as if the account got taken by some other way that didn't involve you. He will believe (If he is reasonable) that this was his fault and noone elses. Hopefully he will not recall again.
Now, sell the account he gave you, and you've made a profit.
I know its alot to do, but the precautions are worth the measures taken.