How about, for someone to post a review, you have to take a picture of yourself with the product. But before you take the picture, you get randomly assigned a number. You must post a picture with that number in the photo. Then either do magic machine learning to check, or have a review process. Better, have it be manual. Get more people in the process, not less. I think this is an awesome idea, which would be completely ruined by fake reviews, but I'd feel much safer if there were like 1/10th the number of products but knew with certainty that a real human vetted and cared about that specific review.