@OP - best story is to say you're using affiliate earnings whether you're legit or not. That's easy to prove if you actually do it, though, and so the buyer-preferred method. Proving you bought with a non-stolen credit card is more difficult since it's difficult to verify who you are unless you're willing to do something crazy like provide a trusted member a credit report emailed by a trusted reporting corporation... but then it'd still be difficult to determine whether or not you've committed full identity theft. It can't truly be proven you haven't hijacked websites for the affiliate earnings, but at least you'd need access to the sites' credentials for a significant amount of time without the original owner taking the account back, so it gives a feeling of security.
Nothing necessarily wrong with you, of course... just a really skeptical community. We've had problems in the past...

AFAIK, though, Amazon eats the loss for anyone who bought stolen gift codes - they don't chase Johns down and take away their credits once applied (or at least, I've never heard of that). -So fwiw.