Tracking down a scent

There's a smell in my (home) office, and I cannot track the damn thing down. I've taken out the garbage, moved the litterboxes to a different part of the house, opened the window, sprayed air freshener, and vacuumed. Finally, I changed my clothes. I still smell it. It doesn't smell like anything the cats/dogs would have done. It doesn't smell like something's burning. It's not old food. It's not coming from outside. It's not even particularly bad, just annoying (if that makes sense). Like a spice you don't particularly care for - if you worked at Cinnabon or Starbucks I suspect you'd eventually get sick of the smell.

Mostly, my office consists of books, papers, and electronic stuff. The futon actually smells good. There's no dirty laundry.

Gah!! I may just have to pack up my laptop and head to school. This is like some sort of psychological warfare.