You guys just inspired me to clean my mouse, and whilst is ball was clean, the rollersthat pickup the movement were unbelievable - the rollers werent touching the ball at all, only the fur that had wrapped aroound it. It was so compact it was like black plastic. I scraped it all out and i couldnt beleive how much there was. I need a cat who can lick this suckers balls more often than i have.....erm......you know what i mean 😛