Twice a year, haul your mattress off the frame for a thorough cleansing. First, vacuum seams, nooks, and crannies with your upholstery or crevice tool to suck up skin, dust, and dirt. Next, check for stains and spots, and treat them. An enzyme-based pet odor remover may clean up many bodily fluids. Or try 1 teaspoon of mild dish soap mixed into a cup of warm water on stains. Don’t oversoak. Too much moisture can encourage mold.