Do you guys clean any new carts you get, be it Atari to SNES or Gen games and how do you store the loose ones?

Right now all my NES carts are in my game case, sleeves or no sleeves. My other loose Atari carts I have at home (from a trade with CS) are on one my new bookshelves next to my three boxed 2600 carts, then my 2 Lunar 2 games with FF7 and 8, then my 6 Genesis titles.