And in terms of trying to game out the fake reviews, I've found relying on the 2 to 3 star reviews are the best. The liars who are trying to trash the product tend towards 1 star. The liars who are trying to sell the product almost always go for 5 stars. 2 to 3 stars, sometimes 4, are usually the people who actually bought it.
Fake reviews aren’t all that cheap, in the scheme of things. Leaving bad reviews on the competition doesn’t have anywhere near the immediate impact on your bottom line as fake good reviews on your own products. I also haven’t seen reports of people being paid for bad reviews, when confessions of people being paid to write good reviews are all over the place.
In case a popular product is simply handled by Amazon or other sellers, they aren't responsible for the quality itself. Bad review of a keyboard on one site is as valid as on another.
Worse, that way you would end up avoiding the "fair players" who don't leave fake negative reviews with the competition.