Try posting a one star review on Amazon within days of a new release. Don't reveal your name or post a review as to why you feel this book is absolute trash. But both you and the author know this lone star will influence other readers not to buy the book. Sure, that hurts economically, but more so it means few if any people will read the story that took months of research and more months to write. That one star also endangers the entire series that went before and might come after. In this case, I am speaking of Lion in the Heather, the latest of the Longleigh Chronicles, which is supposed to be a funny romp of a Regency novel. Granted, some take their Regencies very seriously, and this will not be to their taste. I understand that, especially if they post a review saying so. Also, sometimes, an author can glean some insight for their next book and perhaps avoid a pitfall. A one star review with no commentary is only meant to hurt.
I've been writing for sixteen years and know by now one must grow a skin the thickness of a rhino to continue on. I vividly recall my first troll review on an early book, The Convent Rose. It dropped the day the book was released, hardly enough time to read it. The troll didn't even have the name of the characters right and purposely garbled the plot to make it sound inane. I contacted my editor. If there had been crying emojis back then, my message to her would have contained a dozen tearful faces. She told me to forget about it. I had fans who would like the book and correct the low ranking. She was right. Positive reviews came in slowly and the book ended up with an overall ranking of four stars, probably about right for this short, funny story.
Of course, there is the possibility a person meaning well thought a one star review was great. I had a person once admit to this, but she'd also written a glowing review saying how much she had like the book. At least, this made it clear to anyone reading it that she'd misunderstood the star system. Hey, folks, if you have done this accidently, it is possible to go back and change your ranking, especially on Goodreads. Just go to your review and click on Edit. I am not sure how this is done on Amazon as they rarely take down a review unless it can be proved to be malicious, but with no actual review submitted, it's just an opinion. If a mistake, they could balance that out with leaving five stars and no comment!
One person remarked to my current woe that authors write mostly for themselves. Somewhat true. It certainly isn't for money as most books generate only around a dollar for a copy sold. The rest goes to Amazon and the publisher, so no getting rich unless you sell millions of copies. Big name authors can make big money. Many free copies are dispensed to get reviews, and their legions of fans will punch the five star button whether the book is great or not. Much as I like Nora Roberts, I do occasionally drop a four or a three star review. Some stories are just better than others. However, we do want people to love our books and say a few kind words, especially if the author is mid-list and doesn't get tons of reviews.
Personally, I have never given a one star review to any author though I have read some one star books. I am too aware of the time and effort and courage it takes to write a book and put it out there. Their sales will tell them their book is bad--and lots of other reviewers, but not me. I will not devastate others.