I can always find a few books on my shelves that have been catalogued at some point using the Dewey Decimal System. Most have been rescued from the bargain bin at the little local English library where I volunteered during my time in Spain. I probably even wrote the numbers on the spine, as I had custody of the Dewey Decimal handbook which I'd sweet talked an English librarian into giving me on one of my holidays in England. Noting that these are all in the 900s, you might be able to guess what sort of books I tend to have.