There are lots of books I've enjoyed less than others, but I've had to make a decision to stop reading the books of two authors.
The first was James Patterson. I liked his first few books, but his writing got darker and darker, and it was always, it seemed to me, about the brutal and sadistic killing of women. I started to think that if someone could write like that, they could think like that, and I didn't want to read their books.
The second is Martina Cole. Much the same reason. I liked a couple of her books, but Goodnight Girl was so detailed and graphic, unnecessarily so, that it felt almost voyeuristic and seedy just reading it.
I've read so much crime fiction by so many authors, with really detailed descriptions of crimes and murders, bodies and crime scenes, and I've never felt like those books have made me feel. They're just...off, IMO. So I won't read them, because I don't want that stuff in my head.