I seem to remember being told as a kid not write in books. Certainly, it's not something I've ever done. I recently came across a book discarded by the Edmonton Public Library because it had been heavily, very heavily, marked up by a "reader". Most of the comments were inane, some were profane. All, I reckon, were a waste of pencil lead. I can't know for sure because I just went through the book with a rubber and erased them all, most unread. Now, I guess sometimes comments added by readers are useful; to correct an error for example. And marginalia from a person famous for their interest in the book's subject might even add value to its second hand value. But most of the capitalised scrawl in this book was simply vacuous comment. Whoever was responsible obvious has no friends prepared to listen to his or her thoughts. My overwhelming reaction was "Get a Life".