Orphaned cats and their perplexing toys

I'm going to go ahead and use of my personal quota (1) of cat posts. First off, this post is much indebted to Higgins' classic borrowed cat post. Secondly, I'm not a cat person. Cats are far too human, i.e. moody, for me to pursue them in addition to human companions. Cats sense this about me, and thus we tolerate each other; perhaps occasionally (some stormy night after a glass too many of Chambord), you'll find us curled up on the couch together: me guilty, watchful, the cat practically rolling its eyes. So that's my deal with cats.

That said, last spring my roommate and I offered to take in, for a brief though unspecified amount of time, the very personable cat of some friends who were moving cross-country. It's not that we never heard from them again, exactly, but let's just say they were veritably reabsorbed into the happy, protean world of pre-cat-ownership.

I saw them once, months later, in their new city, and when I broached the "so um when are you going to be picking up your cat?" question, one of them went mute and began strumming his guitar, and the other hyperventilated through choked-back tears. We just want what's best for...[redacted]. They wanted what's best for the cat.

He tolerates and even indulges most efforts to engage him in folly, but what he loves most of all is a good combat session with a NAIL FILE. Yes, a nail file. The bigger the better. He greets nail files the way humans greet a nice fat IRS refund. He cannot get enough of the thing--he'd at once like to be filed by it, demolish it, make love to it, devour it, and in any other way experience & exploit its essence. So that's my cat post. And now, ineluctably, I'm going to ask you fine people: is he deranged? is he special? was he a nail technician in a past life? Do your cats eschew all the goodly toys of the manufactured-just-for-cats world and obsess over human vanity tools? (And alternately, you know, have people ever left you--as in, really left you--with their pets?)