You can filter Amazon reviews by "Verified Purchase" which, unless someone tells me differently, at least means the product was purchased. It's annoying but those reviews feel a bit more honest.
"The compensated-review process is simple: Businesses paid to create dummy accounts purchase products from Amazon and write four- and five-star reviews. Buying the product makes it tougher for Amazon to police the reviews, because the reviews are in fact based on verified purchases."