The clock in my kitchen stopped working, so I took it down to replace the AA battery. I took it down to replace the battery but discovered that the top of the clock was sticky/dusty and just gross. I actually had to scrub it with a pot scrubber to get it clean. It is because it is above the stove, which creates a lot of air borne oil from cooking. This is not uncommon, and a lot of this air borne oil/smog ends up on your tile floor, and in your rugs, and in your upholstered furniture. Regular cleaning will prevent this buildup. Yuck!