I have had a mighty mouse that I use at work on a windows PC. I have had it for a year now and have had NO signs of scrolling ball clogging or erratic behaviour (from the mouse that is). And I am not terribly fastidious with hand cleanliness (I sometimes eat at my desk).
I love this mouse. I would buy the bluetooth version in a minute
I don't even try to use the side buttons but the scrolling and the scroll button work great. I have never had a problem with the right/left clicking but sometimes other people who try it (all PC users) do.
A Look Back at Mighty Mouse