He just happen to have a pack of purple gum in his pants pocket when I did laundry last week ... yes, I'm a nice mom and do both my son's laundry. I stopped checking their pockets before throwing them in the washer. I didn't notice the gum until I took the pants out of the dryer. The gum was in balls still in the foil wrappers, but the gum had been rolling around in the hot dryer making dark marks on the sides and back of the dryer.
So before starting my laundry today, I had to clean my dryer. I'm lucky that I have my washer and dryer on pedestals, so they raise them up higher (not as much bending when doing laundry). I sat a chair in front of the dryer and used a "magic eraser" with a bowl of water and lots of elbow grease scrubbing the sides and back inside my dryer. It looks brand new again.