Memory foam is an altogether different kind of mattress to a regular one, so the cleaning method is different. In particular, you should use as little water as possible because memory foam material is very absorbent. If you find a stain on your memory foam mattress, make sure you only try to clean that area and do not spread too much water around. Make a mixture of soap and water, but try putting that in a spray bottle so that you only use a tiny squirt on the affected area. Then, use a dry cloth or sponge to wipe the area clean of the stain. If you do think you have used too much water, or just want to make sure the mattress is dry, try using a hair dryer to help dry it. Fitting a mattress protector once cleaned can help you reduce the chance of getting unsightly stains directly on the memory foam mattress in the future.