I've heard of folks gaming at least some of these points by offering refunds (through a different channel, e.g. paypal) to buyers to leave a positive review. I

I've heard of folks gaming at least some of these points by offering refunds (through a different channel, e.g. paypal) to buyers to leave a positive review. I don't know if it's true, but it definitely seems plausible and an easy way to buy reviews from 'legit' buyers. Amazon could counter this by offering a big bounty on turning in sellers that do this, and/or financially penalizing them (the sellers) if sufficient evidence is produced.