1 For cleaning stucco on interior walls or ceilings, use a household cleaner and a scrub brush to gently remove stains. 2  Make sure to pat the area dry with a towel when you're done. 3  If the stains aren't coming out using these steps, obtain a soft bristle scrub brush and scrub the area with the Borax/dish soap mixture.arnings. 1  Do not spray in one area for too long. 2  Do not use a pressure washer in place of a garden hose and nozzle. 3  Never spray water from top to bottom if the stucco is not already saturated. 4  Do not attempt to paint over dirty stucco.