Do You Got the Skills?

I was talking with a coworker a while back, and he said something really wise. She said "I love to read, and I can tell whether I have read a good book, but I can't identify why it's good!"

I was impressed. She put into words what I was unable to do. I love to read; ask anyone. If I am not in the middle of reading a book or looking for another good book to read, something is definitely wrong. So why is it so difficult to explain why you love a book?

I don't have an answer today, I just thought I'd pose the question. Thoughts, anyone?