They should also make a trading history thing so incase you get scammed, you can just show proof of the trade that you got scammed on and they will ban the scammer and give you your stand back.
Opg is obtainable? If they are offering a A tier unobtainable for a obtainable, then they are going to scam because overpays are most likely scams. If opg is unobtainable, make sure he is next to you so you can send and if he disappears, get a bad stand so he wont scam your good stand.
Wisteria. They have added a system where the trade cancels when you switch stands and theres also a trade history thing that Odd checks to make sure that people actually got scammed.