I've had similar success by manually avoiding items that look suspicious in any way, and only buying from Amazon directly, or known reputable sellers. This takes _a lot_ of work, and makes shopping on Amazon exhausting, but I don't see how Fakespot would make this any easier. My problem is not so much detecting fake reviews, but filtering out the possible quality items from the sea of junk copycats. It often happens that entire categories of items consist of junk, and you have no other choice but to pick the least worse one. Sometimes you get unlucky, but thankfully Amazon still has good return policies to cover these cases, so it's not a total loss. The amount of returns they process must be insane.
Come to think of it, I'd really like an AI-powered service that acts as an interface to Amazon search, and does this filtering for me. Bonus points for improving search criteria and allowing filtering by country of origin, ranking reputable brands and sellers higher, etc. Since Amazon will never build this, someone please do!