Thank you for the suggestions! These are great ideas, but unfortunately, the limitations of Amazon's API prevent me from implementing them. Amazon has claimed for years that they are cracking down on fake reviews, so if that is true, hopefully with time it will become less of a problem. Thank you for writing!
How about the ability to specify at least 5,000, 10,000 or 20,000 reviews (right now the max you can specify is 1000).
I added 5,000 and 10,000 as filtering options. Also remember that you can sort by number of reviews in most cases.