Every few months, I spend some time searching for the perfect LED light bulbs for my apartment; the built-in fixture requires 6 candelabra-base bulbs. These are hard to find, but there are a few products catering to this market, so I randomly buy stuff to see if I ever get anything good.
I found some LEDs that claimed to have a high CRI and were brighter than normal, so I took a chance on them. There were a couple legitimate reviews and 5 or more obviously-fake 5 star reviews. The LEDs turned out to be not that good. They were bright, the dimmability was good, and the layout of the internal LEDs was quite unique (corncob style but with some on the top, which is great). But they emitted a very greenish light, which makes them unusable. I have a spectrophotometer so I took a reading of the spectrum and, as you'd expect from the visual appearance, they emit very little red light (and no cyan light, as is the typical emission pattern of low-CRI LEDs).
I wrote a review covering these points, the positives and the negatives, and included the plot of the emission profile. This review was immediately taken down because:
1) Your review should focus on specific features of the product and your experience with it.
2) We do not allow profane or obscene content.
3) Advertisements, promotional material or repeated posts that make the same point excessively are considered spam.
4) Please do not include URLs external to Amazon or personally identifiable content in your review.
In other words: please do not include actual data in your reviews. What Amazon prefers is that the seller buys their own product under a fake name, and then says "5 stars: Great!"
This is probably my last Amazon purchase. I might do a proper write-up and spam it around the Internets and see if I can attract the attention of some higher-ups... but probably not. Instead, I will just shop elsewhere. B&H is way better for electronics anyway, and if you just want shitty LED lights eBay beats Amazon there.
Maybe I will also start buying every LED light I can find and doing proper reviews... but there is no business model there to make my time worthwhile. Reviews only work if you can actually find a product that's good and get people to buy it through your referral link. If every review says "you will hate this product, save your money", there is no way to get funding. So the fake 5 star reviews will continue, and everyone will continue to hate LEDs.