Cooking in a microwave is quick and convenient, but often foods and liquids spill and boil over inside the appliance. If the microwave isn't cleaned fairly soon after these spills, a musty odor may develop. Musty odors also sometimes arise from cooking certain types of foods. It's possible to keep your microwave clean and smelling fresh by using some effective, yet gentle household cleaning products. These products are inexpensive, as well.
Spray the surfaces inside the microwave with a spray bottle filled with undiluted white vinegar. Vinegar is a natural odor neutralizer. Allow the vinegar to soak in for about 20 minutes.
Wet a cleaning sponge with vinegar and dip it in baking soda. Baking soda also helps to neutralize odors and acts as a mild abrasive.
Wipe out the inside of the microwave with the cleaning sponge, rinsing and reapplying baking soda as needed.
Wipe around the seal of the microwave's door with the vinegar-moistened sponge. This will get rid of any mold or mildew that may be contributing to the musty smell.
Dry the areas that you wiped down with a clean, lint-free cloth.