Can't believe people still have mice with balls.... no pun intended there... but if you do and you still need to clean them.. then look inside the hole where the ball lives.. there are 3 rollers in there that also collect dirt and should be washed off with rubbing alcohol.

better still - as the ladies already said.. skip the Starbucks and buy a wireless mouse :) .. no mouse pad needed.. no balls to wash.. win win :)