I love used books. But they have to be in a fairly specific condition to elicit a happy reaction on a scale of 1 to googol. The pages have to be faded to that certain yellowish colour, the cover should have some signs of wear & tear, but not too much. The pages should be almost in full condition structurally, with no major tears, and maybe a couple of dog-eared pages. If a book satisfies these conditions, it will make me giddy with excitement. It's fun to look at the marked pages, or where the book seems to naturally open, and wonder if that page was someones favourite. And if so, why it was. Who owned this before? Also, I do enjoy the smell of old books.