I generally don't mind buying used books. In fact, one of the greatest joys in life (my life anyway) is to browse for hours through a good used book store. It's something that happens less and less now that I have small children, who tend not to understand these delights, but every now and then I get into a bookstore and find what I want.
About four or six months ago I bought a copy of Russell Banks's Continental Drift used. It sat on my shelf awaiting my attention and last weekend I started to give it some. I read about seventy pages over the course of a few days (I don't get enough time to read), and I was reading in bed when out of the pages dropped a little slip of paper that I assumed the previous owner used as a bookmark. It fluttered down on my sheet and I picked it up.
The previous owner had bookmarked his/her book with the backing strip to Dr. Scholl's Corn Remover (or Reducer) pads. And a few pads were still attached to the backing strip. Now I've bookmarked with many things in my literary life, from ATM receipts to paper towels to actual real bookmarks, but I've never used some sort of medicinal supply to do such, and certainly not something related to my nasty feet. But I suppose they were right at hand when needed.