What would be Amazon's best possible approach to dealing with this? Does there exist software good enough at distinguishing potentially fake reviews from real ones?
I've never published a dishonest review, but I have reviewed a product or two that I bought somewhere else (not on Amazon), but I certainly "bought the product."
Yes it still means a person can buy the book, then give it a bad review, then return it, however the effort to do this would be higher AND there would be a purchase pattern that begins to show itself.
When the purchase price is so low, astroturfing with "verified purchase" reviews looks to be quite feasible.
I wonder if Amazon has enough info to create a Googlesque filter bubble, so reviews are per user weighted to account for reviewer\user interest overlap.