This is an interesting question. It all depends on the material of the duffle bag. Knowing what type of material you want on your duffel then it can make it easier for you to clean it. Some of the bags like Migrate Duffles have a water repellent material. This not only means that they are durable but also the easiest to clean. When cleaning use a washing cloth and a mild soap. Spot the dirty parts of the bags, wipe them off and hose clean them with water. Dry them out in the sun. to make your duffle bag long last, normalize hand washing their exterior and interior.