The next time you squeeze a lemon, don't toss the fruit away. You can use the residual juice to clean things around the house. The natural citric acid in lemon juice helps break down stains, and it disinfects, too. Rub cut lemons over laminate countertops to remove stubborn stains. Rub lemons and salt over cutting boards to scrub them clean and sanitize them. If you have clothing with rust stains, soak the stain with lemon juice and cream of tartar, then launder as usual. It should get the stubborn stain right out.