i just know some scammer selling the illegal GC card. and leave the victim a mass.
who will tell me how to prevent it.
or would anyone rank the risk of the GC type or the trading place?
Escrow can not help in this case, you should ask the seller how did he get for example the amazon gift card, can he prove it? There are some websites which give the payment through amazon GC so they are safe to use, but some people buy them in an illegal way so you should always ask for the source of this GC, otherwise you should trust the seller.