Those with tender hearts, I advise you to not read this article: Confessions of a Book Abuser - New York Times. Unless you like the willful destruction of art... well, then go ahead and relish it.
As for me I was brought up to treat books with respect, no leaving a book spreadeagle on the edge of the couch, no dogearing. Even making annotations in book has been difficult for me. Through two degrees I found it hard to write in books unless it was an already beat-up copy I found used.
I don't think books should just be left on a shelf, obviously, but there's a difference between an obviously loved and well-read book and one that has simply been abused. The reason, Mr. Book Trasher, that we treat books with respect and not put them in the washing machine is that we want to keep the book around to refer to, to read again, to share. That's hard to do if the book is holding up a table leg.
But then again, do what you want with your James Patterson books.