If you don't care, just say "That's nice," and move on.

If someone lets it slip that they've written or are writing a book,

Or if they've decided to tell you that they've written or are writing a book,

Or you find out that they've written or are writing a book,

And you ask them what it's about,

If it's not your cup of tea,

It's not your job to make them feel bad.

It's not your job to tell them that you met someone who wrote a book like that once,

And that you thought that person was kind of sad,

Even if you don't say it in those words,

But give the impression that you thought that person was a loser.

It's not your job to make this new person feel like they're a loser too.

If you don't care about the story, or the genre, at least consider the time, effort, and dedication it took to write that story,

And keep your other comments and thoughts to yourself,

Especially if they didn't intend to tell you specifically,

If you just happened to be on the fringes of a conversation,

Or butted in.

There are enough people out there breaking others down.

You don't need to be one of them,

And give someone the mental equivalent of a condescending pat on the head,

Because there are probably things you like to do that would make others do the exact same thing to you.