Want to stay out of "Amazon jail" and in good status with the FTC?
Whether you're a reviewer or an author/publisher, it's good to know the rules.
The Federal Trade Commission is responsible for enforcing laws that govern reviewing products online and receiving items for free.
You can read all about it in the articles linked below but in my (non-lawyer) understanding, the main point is: if you review an item you received for free, you need to disclose that fact for your own protection.
You also need to make it clear that you were not compensated for your review.
Amazon—naturally—has its own rules on the subject. The article linked below explains the intricacies but the hitch for this online retailer seems to be the phrase “in exchange for” because to Amazon, that is the same as saying that you were compensated for your review.
From the article and linked pages below, I gather that you will be able to stay out of "Amazon jail" (that is, when you are prevented from leaving ANY reviews) if you make it clear that you are not being compensated in any way for your review.
However, some reviewers choose not to make any disclosure when they review on Amazon because the danger of losing their reviewer privilege, or getting the author in trouble, is too high.
What you do is up to you, but the language below seems safe to use:
I received a complimentary copy of this audiobook, and I am leaving my honest review.
I received a copy of the audiobook at my request, and the opinions here are my own.
I received a free copy of this book at my request, and I voluntarily provided this review.
I was provided a free advanced listening of this book. However, all opinions shared are my honest thoughts about this book.