This seems pretty simple to me. I mean, if a friend recommends a book to me and squees about loving XZY things in it, even if I might not pick up on those elements normally, I'm going to notice them when I read the book because they've been pointed out. Also, if a friend of mine and I have similarities in things that affect us, it would then make sense that I'd have a similar reaction, especially with those things already pointed out.

I think a suggestion that's been made is good -- find books on your own, not recommended, and see how you react to them. More reading is never a bad thing, anyway. ;)