Many Things Do Not Need to Be Cleaned After Use.

People tend to think of all of the things that need to be cleaned after they are used, such as laundry and dishes. These pessimists ignore all of the useful things that do not in fact need to be cleaned after use. For your benefit, here are several examples:

1.) a pizza
2.) a cruise missile
3.) the fundamental theorem of calculus
4.) a route to an alien planet, such as mars
5.) any self cleaning device (particularly stoves and robots)
6.) lossless data files
7.) antimicrobial pens (yes, these do exist)
8.) cds/dvds (they work best when cleaned before use)
9.) dental floss
10.) pants