Well, the five-finger rule would blow quite a lot of books I have read off my shelves. Any Poirot novel, for starters -- I mostly guess at the meaning of his numerous French exclamations and remarks.
But what it would most blow of the shelves are my dictionaries. I have several of historic slang, two of American slang -- and I read them all from front to back as soon as I got them.
I take the view that if I discover a word I don't understand, it suggests my literacy is not up to par. What I do in practice is reach for the dictionary - not the one on my kindle, but the two-volume Shorter Oxford right behind me as I type. And, being a word-nut, I read that from A to Z when I bought it, though not in one sitting.
I also have German-English and Italian-English dictionaries within reach, both acquired when I needed to understand something.
i guess I'm just a compulsive reader.