I don't think there's anyone that would be impressed by me having read a certain book so there's no point in making it up. Some people I mix with watch the worst TV ever so I should have no shame in my bookish guilty pleasures... and I don't!
Sometimes I might play down how much I hated a book if in the presence of people who love it and look like they might hit me if I'm mean. I won't pretend I liked it though, just say it wasn't for me and move on. We all like different things so you can't judge a person by the cover of the book they're reading!