Paid reviews are forbidden by most websites, and when a big website gets fed up with paid reviews, they start suing those who write and sell them.
There's the matter of ethics, too. Readers would like to see some real reviews before buying a book, and if they get deceived into buying something that's very much not what the review promised, they feel disappointed. They feel that somebody openly lied to them to get them to spend their money on something they ended up hating (and can you say that they're wrong to feel that way?). And then they return the goods and possibly complain to the website. Mass complaints and refunds are, of course, an incentive for the said website to strictly forbid paid reviews.
Several years ago, I wrote some paid reviews for a website, but they were purchased by them, and used for promotion (and I still refrained from claiming that the books were good or bad, I merely stated some easily verifiable facts about the topics, the plots, the characters...). On Fiverr, I don't offer book reviews, only book blurbs (the obvious promotional piece placed on the cover). Paid reviews are forbidden, anyway. There was even a big lawsuit because of paid reviews. And yet, someone wanted me to write a review of their book, so the bit of news that I mentioned in the title is that I've changed the FAQ of the book blurb gig to add that no, I do not write reviews. Why is it even necessary to state that I don't offer a forbidden service? I don't know, but it apparently is, and I can only hope that it will help. Another thing I've added to the FAQ is that I don't offer discounts; with the base price of $5 for a service that can't be automated, offering a discount doesn't make sense, no matter the size of the bulk.
And the friendly reminder? I've got a Facebook page, and I even post stuff there sometimes! If you wish, check it out and like it.
