When you like everything in a book except the characters.

Of course, I'm exaggerating about "everything", but you understand me. There is a book that you like or even have in your favorites. And when they ask you about it, you say what a cool story it has, what an atmosphere, what a good writing style the author has. And then they ask you about the characters. And then you realize that at best way they are cardboard.

For me, such a book is "Babel" by Rebecca Kuang. I liked the way the author conveyed the atmosphere of Oxford. I liked the second half, which I found fascinating, and I liked the author's writing style. But the characters were blank cardboard. Only Robin Swift was of any interest, and not by his character, but by the dilemma of who he was.