Scrape off the loose bits in the box with a plastic scraper or old credit card. Wipe with paper towels. That's it. If you feel the need, every few years you can use oven cleaner, then re-season, but it's really not necessary, unless it would make you happy. If you feel the need to "sterilize" it for some reason, crank it all the way up and let it burn for a several hours and wipe it out. I have a #1, so the racks and rack guides easily fit in the dishwasher. If I had a larger smoker, and the racks and rack guides did not easily fit in the dishwasher, I would totally be more lazy about cleaning those, and probably never clean the guides. I think you have to clean the racks however. You are not sterilizing them by heating over a blazing hot fire like you might for a grill, where you can just brush off the gunk once they are heated. Maybe the 2-4 owners here can give their tips on cleaning the racks. Maybe at the end of the smoke just crank up the smoker and let it burn off?