Two individuals reviewing each other's works is against most websites' terms of service, including Amazon's. That activity is also against the FTC regulations, which governs US public publications. A review swap is a biased testimonial. It is a violation and can cause accounts to be deleted permanently.
In addition, an author should never write a review about ANY book in their genre. It is a conflict of interest. Whether they review that book well or poorly, it cannot be an unbiased post. They have a vested interest in how others do in their genre. It would be like an owner of a Burger King reviewing the McDonalds across the street.
Here's an article in The Guardian about Amazon actively deleting reviews written by fellow authors -
The Guardian on Amazon Reviews
The article states that Amazon's rules are:
"sentiments by or on behalf of a person or company with a financial interest in the product or a directly competing product (including reviews by publishers, manufacturers, or third-party merchants selling the product)" are not allowed.
Authors can't "review swap" where they trade reviews, with the expectation that each support the other. It is, again, not "unbiased." Amazon actively runs computer routines where they look for those trades and severely penalize both parties. If someone has done a review swap in the past and not been caught it merely means the odds are stacking up even higher against them - and when they ARE caught their evidence of past wrongdoing will weigh heavily against them in the judgement.
New York Times -
New York Times on Review Swaps
"Giving raves to family members is no longer acceptable. Neither is writers' reviewing other writers."
This includes review "round robins" where each author reviews the next person in line. That is still a review swap. Amazon will find the chain - and it will penalize or destroy all accounts involved.
Amazon Vine is NOT a review swap
Review swaps are wholly different from the Amazon Vine program, which some authors bring up as a counter to this issue. Amazon Vine is a program on Amazon where high-ranking reviewers get free products from Amazon in order to review them. The Vine program is in essence the same program that every publisher already has in place, to send out free books (or items) to unbiased reviewers. As an example, I get deluged with products from Vine, from Penguin books, from yoga vendors, and from many other vendors, because I have a solid track record of a reviewer. I review all of those things in a wholly unbiased way.
Sometimes there's a thought from a non-Vine person that Vine reviewers somehow review things "well" (in a biased manner) in order to get more free things. That couldn't be further from the truth. Our Vine status is guaranteed. Many Vine reviewers delight in being extra harsh on products to prove the reviews are authentic. If anything Vine reviews tend to be intensely thorough and harsh because us Vine reviewers care not about the manufacturer's egos but about racking up high reader votes. A thoroughly written, highly critical review is a great way to get up-votes (it reads as wholly authentic), which means a higher ranking, which means more high-quality vendors send you things. We care about pleasing our readers with high-quality in-depth "looking under the seats" reviews which earn us votes. We don't care a whit about making the manufacturer happy.
It's like being Consumer Reports. That is what we aim for. We want to be as thorough as we can and point out every potential issue. That earns us stars.
Because we then earn those high rankings we get deluged with high quality products by vendors who think they'll be the ones to earn the 5 stars. We want the high quality stuff! I really don't need more "junk" sent to the house!! My house is full of junk. I want only 5-star items sent to me, which I ensure by giving lower quality items appropriately harsh reviews. The last thing I need is any junk sent to me.
So, back to the issue at hand. Authors should not trade reviews with each other. It's unethical, it's against FTC rules, and it's against Amazon rules. It is the path toward account deletion which is the death knell for any author.
Avoid At All Costs.
If you need reviews, get them the ethical way. Market your book so you get more authentic readers.
What Does It Cost to Ghostwrite a Book?
Lisa Shea's Editing Services
Lisa Shea Free Ebooks
Lisa Shea Full Library of Published Books
Getting Your Book Published
Writing Tips and Online Books
Lisa Shea Medieval Romance Novels
Online Literary Magazines
Lisa Shea Website Main Page
You Can Get Free Gift Cards For Shopping, Searching and Discovering What's Online at Swagbucks.com