I was browsing my library and realized I have a few books with typos and a few of them are quite considerable and one of the books lacks a page in a classic novel. I have always been told that any mistake made in printing a book can make it worth more, particularly in the case of a first edition, but I am not aware whether the same thing holds with the present day paperbacks, or only with older hardcovers. As an illustration, is a typo on page 50 a significant rare find in a book that the publishing house should be proud of or simply a bad batch of paper? I wonder whether there are people in this crowd who majors in book collecting and what exactly sorts of errors the hobbyists seek and where I can find these editions evaluated.