I'm a very active Goodreads reviewer. (You can add me on Goodreads here.) Since I read a good number of NetGalley books, and some of those books are categorically Not So Great, I end up writing a fair number of bad or so-so reviews. Sometimes, I get replies that my review is too harsh (as if holding authors and editors to standards of grammar and cohesive plots is "too harsh", but ok) or a "doozy."
I read a lot of romance novels. And I'd say about 75% of published romance novels are categorically "bad." They might be "so bad they're good" or that kind of guilty pleasure bad. But they're still bad, in terms of plot and characterization. That's what I review for: is the plot cohesive? Are the characters well-rounded? Are their actions believable within their universe and personality? No? Then, you have work to do.
There are a pretty high number of Goodreads users who start reviews with something like, "If I don't like a book, I don't finish it or review it." So basically, they only review the books they like. That's fine, but how does that help other readers decide if a book is worth their time? How does it help bring attention to something a newer author needs to work on? How does it help people find diverse books? Here's the thing: it doesn't.
It's not possible to like everything. And that's ok.
I love reading! I even love reading terrible books (really). But if I start a book with all 5-star reviews and realize halfway through it feels like it was written all in one sitting with absolutely no editing work or attempt at cohesiveness, well, I'm gonna be a little disappointed. And I'll start to question my sanity. What are those 5-star reviewers seeing that I'm not? It leads to me feeling a little, well, confused. Then I remember: so many people just don't write bad reviews. They don't want to do it.
I totally understand. When you're reviewing a book, you're reviewing someone's work. Even if it is bad, it's something they worked hard on. But that being said, no one can improve if they aren't told how to. They can't change things if they don't know they need to, if they don't know that it isn't working. As a writer who really struggles to share my work publicly, it can be stressful to ask for feedback on something that feels so personal--but you need feedback to grow. Even professional author's need readers feedback to see what works and what doesn't.
Readers also need that feedback to make better decisions about what books they want to read.
So, is it bad to write bad reviews? Is it mean? Should I stop doing it? No, absolutely not. Writing critical reviews of books isn't a personal attack on an author; it's a necessary part of interacting in the literary world. We have to be critical some times to effect change and improve literature.