Part of the problem is that we're using reviews for multiple purposes: Amazon mostly seems to want reviews to be for a type of product and is fine merging revi

Part of the problem is that we're using reviews for multiple purposes: Amazon mostly seems to want reviews to be for a type of product and is fine merging reviews from any seller claiming to sell that product because at least then all the reviews will be in the same place. This is still subject to the problem you're describing (how broadly should different parts of a single review apply). That isn't the whole story though. For a lot of products people already know exactly what they want and are using reviews to figure out if the seller is able to provide it without selling a counterfeit, without shipping it 2 months late for 2-day shipping, without selling a used model as new, etc.... This still suffers from a granularity problem (does the seller generally do a good job and just not know how to package N64 controllers), but that granularity isn't as severe of an issue as with arbitrary products.