I also enjoy some of the more interesting bad reviews. I once came across a one-star review that I initially looked at because it was the only low rating on a book that had received over 100 4- and 5-star reviews. As I read it, I noticed that the reviewer kept referring to the author in a very familiar manner and got the feeling that they knew each other. It was very detailed and rather scathing. Almost brutal. The author responded, but only to basically say, "Thanks for your extremely detailed thoughts. I'll keep them in mind as I write the next book." The reviewer responded with, "Well, I told you when you sent me the book that I wasn't going to be nice just because I'm your mother." I really wish I could remember the name of the book, because I'd love to see if that exchange continued.
I rate all the books I read on Goodreads, but I no longer write reviews for indie books if I rate them less than four stars. Two experiences of being confronted by disgruntled authors over three-star reviews soured me on that. Ironically, both had given their books away in exchange for "honest reviews" on a site I used to frequent. I'm fine with a PM or email asking for more info on the issues I felt the book had, or to ask for suggestions (one author did that and it was a wonderful exchange) but to call me out publicly to dispute my review in a confrontational manner was a bit much. On the other hand, maybe I should feel flattered that my opinion carried enough weight to warrant a response.