the things we don't clean (little moment of compulsion #5)

My mom taught me to make sure to clean the light-switches, because people rarely do.  I realized today that the same thing applies to lamp switches, doorknobs, and the faces of doors right above the doorknob--where people catch the door when it swings or where they push it when they don't need to turn the knob.    What else gets touched often that isn't on my radar of things to clean?