This is a good topic for discussion. I have to admit, every time I post a review, I am mindful of my own stories and my own shortcomings. Any author deserves a respectful review, even if you hated the book.
Which brings up a point I’ve been wondering about. In trying to support other authors, I’ve read some books that are not in my preferred reading genres. The books were truly fine, but I didn’t enjoy them because I don’t like that kind of book. So what do I do? The author is expecting (sort of) that I’ll post a review. Do I just say, “good book, good writing,” and avoid specifics? Does it come across as damning with faint praise?