Maybe 90% of the time reviews are just promoting a product advertised in the publication or website running the review.
Rarely is there anything negative said about the product. Occasionally there’s a rave review where you can sense it’s more than just a plug.
On the rare occasion when the product is not advertised and there’s no financial incentive to praise it, you might find a sincere review. (Absolute Sound was like that many years ago, when the late, great Harry Pearson was the publisher.)
And if that reviewer thinks highly enough of the product to actually buy it - at the retail price, you can be reasonably sure there’s some genuine value in his opinion.
Here are some examples of that sort of review:
https://silversolids.com/frames/revbuys-2.html