Inexpensive flat paint does not hold up well to scrubbing. It can wear off or show light abrasions. Choosing a high-quality flat finish, however, will give you a touch more durability for cleaning. To clean flat paint surfaces, lightly dab or rub with a soft cloth and warm water. If stains persist, add a small amount of vinegar to the water and repeat process. Finally, you can use a cleaning eraser for stubborn spots. Avoid using abrasive or harsh chemical cleaners.