The reason I ask is because I found a deal that seems REALLY fishy but the guy looks legit. He has 100% positive feedback with 70 reviews, all for the same item. He is basically selling $500 moneypaks for $375. Seems a bit off right? What are the chances this is a scam?
Yes, feedback can be faked. Vendors can make buyer accounts and buy from themselves, they can create super cheap listings and puff the # of reviews with those, hackers could purchase an established vendor account.
Then again, if it is real there is a reason that the moneypacks are cheap. They're probably carded, stolen money is used in some way. There is no such thing as free money; if there was no catch the vendor would just do and endless cycle of purchasing them from themselves and making millions. As they're 25% off my bet is that this isn't catch free. ;-)
Ask the vendor, they may be willing to tell you the moneypack origin. If they give no details but insist everything is legit, back off. If they explain they were purchased using stolen credit cards, okay, I get that.