Should You Review A Book You Haven’t Read?

Today’s post concerns a growing trend I’ve noticed lately on Amazon, people reviewing books they haven’t read.

I’ve seen comments by reviewers who openly state they didn’t read the book, and others who state they merely flipped through the pages, and others who state they only read a few pages and then quit.

What do you think about this practice? Is it fair to the author? Is it fair to the potential buyer of a book who is checking reviews to see if they want to purchase?