Lot of trust is needed when transacting Prepaid Cards and Gift Cards with a seller. There's no way to prove if a gift card is valid if the seller already used it. Even reliable sellers sometimes are scam, they reap buyers once in a while after building trust with them.
As the comment above me already stated, buy gift cards from trusted companies.
Because we (in my country) don't have access to international cards (visa,master,paypal,..) , we can't buy Gift Cards from trusted cmpanies. I spent a lot of time looking for a secure way to buy Google Gift Cards using bitcoin, but almost found nothing. Even in btt forum here, it remains the same trust problem.
I want to ask if anyone knows about the best way to sell google cards and if anyone (trusted forum user) knows a trusted seller that can accept bitcoin.