The short answer: Don’t! But if someone already committed this sin, go ahead and add more. There are paints designed for stucco, but each paint layer negatively affects the exterior’s breathability (or “perm rating”). The less an exterior system breathes, the longer it takes for moisture to leave the wall cavity, creating a potential environment for mold. Stucco doesn’t bond to paint, so eventually paint will have to be sandblasted off your house. Sandblasting is a noisy, messy process that won’t endear you to your neighbors. The best solution? Re-stucco by applying a thin layer of colored cement.
“Just a note to thank you for the beautiful job you did when you stuccoed my house. And the wonderful cleanup job.”