In the current day you need to assume all numbers that represent large groups of people are fake, or at the very least heavily massaged. Polls, ratings, upvote counts, likes and retweets, "scientific" data, vote counts.

The only time it's trustworthy is when they are low numbers, or the mass media is trying to desperately convince you away from something.

And specifically with Amazon, the Chinese companies often ask you to give a positive review in exchange for a gift. The gift sometimes costs more than the product you bought in the first place.