To freshen up and dispel any lingering smells in your microwave, put a bowl; half filled with water in the microwave with 3 or 4 slices of lemon in it. Cook on full power for ONLY 30 seconds (See waning below).
Another way to cut down on the smells that are created by cooking such things as bacon in your microwave is window cleaner. Spray the inside of the oven with a window cleaner that contains ammonia. Then wipe clean. The ammonia in the cleaner will prevent smells
Microwaves can harbor odors between uses, which can change the smell of foods subsequently cooked in them. Keep a cup of baking soda in the microwave between uses to keep potatoes from smelling like bacon or other unusual combinations!
Warning: It is important not to heat fluids in your microwave for long periods as they can become super heated, this can cause an irruption within the fluid even after the vessel has been removed from the microwave. This irruption can send scolding super heated fluid in your direction.