99% of the time, I don't write bad reviews. The reason is a simple one. If I didn't like the book, I don't want to waste any more time on it. Occasionally I will write a couple of lines on Goodreads after I've given a star rating and I will send a quick note to the publisher to let them know what I didn't enjoy about the story and why I won't be reviewing it. But that's about it. I'd rather move on to the next book and hope it's something better.
I will sometimes read other blogger's negative reviews, but the ones with 4 1/2 - 5 star ratings are more likely to grab my attention.
So what about you? Do you write negative reviews?