Mine was a laser mouse and seems to have sucked fluff and 'other organic matter' in through the slot which the scroll wheel pokes up through.
Looking at Mr Pilcher's post, I wonder whether one could not have one of those very large tracking balls set into the seat of one's office chair, so one could simply twist and shake one's behind to move the cursor. Secondary advantage would be getting a bit of exercise while on PPRuNe and warding off DVT. Terciary advantage would be massaging one's piles.