A boy sits and reads a Russian picture book. Rather than simply admire the cuteness of the scene my mind slips immediately into bookseller mode: "That cover is dog eared in the corner and has signs of handling wear. I wish he'd turn so I could see the name of the publisher on the spine, not that I could read it anyway. I see that the spine is peeling and it's likely there are scuff marks on the back cover. The book is probably worthless."
I enter Borders and am incapable of browsing for books that I might enjoy. I automatically scan the spines of the books, looking at the names of publishers. "Look! That one is a Wiley! Probably worth at least $20." Or, "Look! A Da Vinci Code hardcover! I wonder if it's a first printing, first state, with the error on page 152!" Then I remember I'm in a retail bookstore and there is no possibility that this is anything other than the 8000th printing. No wonder I buy all my books online now. Going to bookstores is no longer restful, now that I'm a bookseller.
I walk past one of my children and note that they are reading a book. Instead of merely appreciating that she is reading, and not fighting with a sibling or using the computer, I think: "That looks like a scarce title. I don't think it belongs to our personal library. Oh no! Is she reading a listed book? They know they aren't supposed to do that! I'd better look it up on the database. If it's not in our database I'd better research it and see if it's worth anything. But it looks like she's enjoying it. I'll have to wait until she's asleep."
So, as you can see, one CAN judge a book by its cover. All. The. Time.