Jeaniene Frost addresses authors on the etiquette of dealing with reviews. Authors should take note of Frost & Andrew's words, because there are things worse than turning out a bad book. Defending the validity of your work to the point of attacking would-be fans & readers, will only get you viewed as a crazy author that should be avoided at all cost. Case in point, my crazy author run-in a few months back. You can read Frost's full post here.
Author Ilona Andrews sums it up this way:
What about negative reviews, the ones that make you cringe?
Say nothing. Say nothing, say nothing, say nothing.
But what if they said this unfair thing…
But they brought up a really good point…
If you argue with the review, you look unprofessional. You are a weakling who can’t take criticism.
If you agree with the review, you look unprofessional. You are sucking up in hopes of future positive reviews.
You can’t win. Remember the guiding principle: if you are an author…you are not a person. You are a representative of a brand. If you have to say something, if you just can’t help yourself, say, “Thank you.” You must find your inner customer service representative, smile, and say, “Thank you so much for taking the time to read the book.”
It is really, really difficult to find that customer service representative sometimes. So if you can’t trust yourself to smile and say thank you, say nothing.
Thank you or nothing. From the business point of view, there is no third choice.