I belong to several writer's forums, and one of the most discussed topics is reviews. Writers are constantly wanting to know how they can get their work reviewed. There are all sorts of suggestions on the forums on how to get reviewed. Some suggest professional reviewers who will review your work for a price. There are reviewers on the forums who offer such services.
They claim that their reviews are impartial and unbiased. But at the same time, their offers are worded in such a way that that their reviews will help your sales...in other words they are saying that you can expect five stars from their reviews. Otherwise how could they help sales?
Other writers suggest exchanging reviews. I'll review yours if you review mine. Of course, all writers involved in the exchange would be expected to give glowing reviews. Any writer who gives his fellow writer a less than glowing review with only three stars can expect the same in return, even if the bad review was justified.
Still another suggestion is to offer your work for free for a specified period, in the hope that if enough people read it, certainly a few will give a review. But many writers complain that large numbers of their free books were "sold" without producing a single review.
Fact is, the vast majority of readers just don't write reviews. If they love a particular book they will simply tell their family, friends, and neighbors about it, which is probably as good as or better than a review. On the other hand, if they hate your book they will also tell their family, friends, and neighbors.
In reading some reviews, it is glaringly obvious that the writers had friends or family members writing the reviews. Some writers with lots of reviews even admit to having family and friends doing them. However, they claim that they demanded of their family and friends that all the reviews be impartial. Yes.
Some writers claim to have gotten awful reviews from fellow writers in the same genre who are in competition with them. Others claim that bad reviews come from enemies trying to hurt them in every way they can. Still others say that there are malicious people out there who give bad reviews for the fun of it.
Some people love to review. They enjoy reviewing books in much the same way that authors enjoy writing them. Many reviewers are proud of the long lists of books they have reviewed. They take pride in believing their reviews to be fair, unbiased, and impartial.
Actually every review is biased to some degree. If the reviewer is partial to flowery prose, she will be inclined to give better reviews to such writing than to tight, unembellished prose. On the other hand, a reviewer who is partial to tight prose would be inclined to give bad reviews to wordy, flowery writing.
Every writer has his/her own style. A reviewer may love or hate your particular style, and this will be reflected in the review. A reviewer may be partial to graphic descriptions of violence; another reviewer may be turned off by same. Two reviewers may have vastly different feelings about graphic descriptions of sex.
My own feelings about reviews is just to publish your work and let the chips fall where they may. Only a few of my books have been reviewed. There were several with five stars and one with only three stars. The one with three stars is among my best sellers. My #1 best seller has not been reviewed at all.