I'm actively wondering whether it would be possible to build an external ranking-by-review system, since Amazon's <Sort By Best Avg Review> system has been fully gamed, and I use a completely different algorithm.

Meanwhile entire categories are completely full of fraudulent junk -- start with LiPo 18650 batteries. One seller was even using Tesla's brand and logo claiming to sell their batteries. It disappeared a few days after I reported them, so Amazon does appear to be doing something, but it's completely inadequate.