(Full disclosure: Klausner gave my book a favorable review)
This is a non-issue.
1) I do not know Harriet Klausner personally. I have no way to know whether she reads the books she reviews. Time magazine and the NYT have tracked her down. She's a retired librarian and she says she's a speed reader.
She posts her reviews under her real name. This is her whole thing; she's tied her identity up in Amazon reviews to a greater extent than perhaps anyone else alive. As a reviewer, she is a better-known quantity than just about any customer reviewer on Amazon.
Either you find her reviews helpful or you do not. As of right now, she has 108,000 "helpful" votes.
2.) The fact that she gives only 4 or 5 star reviews is not at all controversial. On Amazon, anything less than 4 stars is a negative review. I generally don't buy or read books I don't expect to like, so I've got no cause to give bad reviews on Amazon.
Perhaps we'd be better off if a five-star review was reserved for extraordinary works and three stars still connoted a worthwhile read, but it does not. An average rating of about 4.2 signifies an acceptable book on Amazon, and an average rating of 3.7 suggests that readers were disappointed.
Also, when readers don't like books, they tend not to finish them. That's especially true of readers who don't pay for books, and don't get paid to review them. I tend not to read books I expect to dislike, so I have not read a book in the last 3 years that I felt the need to go on Amazon and un-recommend. Therefore, if I were a reviewer, I would not have published a review below 4 stars either in the last 3 years.
3.) To the extent that Harriet Klausner's reviewing practices are problematic, Amazon has already done something about them. Klausner became the number 1 Amazon reviewer at a time when reviewer ranking was calculated according to a reviewer's total number of helpful votes. This gave an insurmountable advantage to people who posted a huge number of reviews.
Years ago, they changed the ranking algorithm considerably. Klausner's current reviewer ranking is 1616.
4.) Most professional media reviewers, whether of books, film or music, review publisher-provided review materials. Professional outlets do not post FTC disclaimers on their reviews. What constitutes a "relationship" or an "endorsement" under the FTC guidelines is vaguely defined, and I am not aware of them ever being enforced against a book blogger, or anyone at all.
It has not traditionally been an ethical requirement of a reviewer to disclose that review materials were provided by a publisher, though it is a widely-known common practice to review publisher-provided materials. This obscure FTC guideline does not create a new ethical obligation.
Many top Amazon reviewers receive review materials and do not post disclaimers, either because they don't know about the relatively obscure FTC guidelines, they've dismissed what they've read about FTC disclosure requirements as Internet misinformation, or because they have concluded that the guidelines do not apply to their reviews.
I assume all top reviewers get their books for free, and I still trust them more than I trust non-top reviewers. People get to be top reviewers by writing reviews that strangers find helpful.
5.) ARC-selling is annoying. Secondhand book sales are kind of annoying. Neither of these activities pays royalties to authors. But the fact is, obscurity is the biggest challenge any author has to overcome, and that's why all authors want their publishers to send out lots of ARCs, despite the fact that they may be resold. A lot of authors don't get ARCs, and wish they did.
Secondhand sales of physical books, ARCs or otherwise, are an absolutely trifling problem compared to digital piracy. And as a "racket," or a scam, selling secondhand review materials isn't very lucrative. Booksellers make most of their money selling lots of copies of popular books. Klausner's review habits get her one copy each of thousands of different books, many of which aren't in high demand. Even if you believe she can sell every single book she gets from publishers on Half.com, she has to do a lot of envelope-stuffing, listing management and trips to the post office for a profit of a couple of dollars per book.
6.) Klausner's review of my book is not derived from any of my publisher's marketing materials. She refers to characters and events that are not mentioned specifically in any of the promotional stuff, so it appears she read at least part of the book and wrote several paragraphs about it.
I know my publisher sent my book to Klausner unsolicited, and I know of several other reviewers who have higher current reviewer ranks that either bought the book based on professional reviews or had to request it from Vine or Netgalley. I am actually a little bit frustrated that publishers aren't doing a better job of cultivating some of these other top reviewers, since these people seem to maintain groups of readers who place a lot of trust in their recommendations, whereas Klausner's influence is more diffuse since she reviews so much.