Even if the deal becomes extremely shady? Like account's getting recovered then given back with money taken off because of a "sibling" or other such excuse?
If they take anything back that they gave to you during the trade, they're scamming you. If you take anything back that you gave them during the trade, you're scamming them. The only exception is if it's mutually agreed to that a refund or trade back of some sort should take place.