It can be a jungle out there, particularly with the internet. I am nearly certain I have experienced people who take a well-critiqued book, don’t write a review, but simply give it a “1’ rating out of ‘5’ to diminish its overall rating.
It’s happened to me. Though, obviously the internet can get a lot worse with outright bullies of fragile adolescents and major, fraudulent schemes that dwarf those unpleasant raters.
Some writers respond to the worst of the critiques with thoughts like, anyone can criticize, but few can write well. One man a few years ago joined the writers and was quite successful.
That was George S. Kaufman, 20th-century, drama critic and comedy writer, who was wont to say, “I didn’t like the play, but then I saw it under adverse conditions–the curtain was up.”
Not as funny for the playwright.
Pilgrim on a Long, Long Journey 