What if a critic hasn't played fair?

An acquaintance asks, "What do you do if the critic hasn't played fair? What do you do about negative reviews?"

Nothing.

Do nothing in public. Don't try to correct the record (unless the review has clear factual errors, and even then stick to the facts). Don't try to justify or explain yourself.

Privately console yourself that the reviewer is an idiot.

A case in point: Here is one of the 24 one-star Amazon reviews for a book I thought was a masterpiece: "Extremely hard book to read and understand what was going on. Could not even finish it. Could have been summarized in two pages with life principles it was raising." This reader is an idiot.

I am not alone in my admiration. The book has received 509 four- and five-star reviews, by the way.