1. Grab a bottle of McNett Mirazyme.
Mix about a half-ounce into a gallon of water and use a nylon-bristled vegetable brush to scrub the gross spots. (If mildew plagues your whole tent, dissolve a full ounce of Mirazyme into a bathtub and scrub down the whole thing.
2. Set the tent up outside in the shade to let it dry.
3. Now mix 1 cup concentrated lemon juice (the type that comes in those little plastic lemons), 1 cup of table salt, and a gallon of hot water. Use a sponge to bathe the whole tent. Then let it dry thoroughly before packing.