Freshen a Garbage Disposal: Sprinkle baking soda in it along with a few drops dish-washing liquid. Scrub with a brush (a new toilet brush works great), getting under the rubber gasket and all around the inside. Then, turn on water and let the disposal run to flush thoroughly. For a fresh citrus scent, throw in a few cut up lemons or limes and run them through, too, using lots of water.