Stucco is one of the most difficult surfaces from which to remove graffiti for a couple of reasons. First, its texture, with so many fissures and surface. Second, it is relatively soft. However, a liberal application of Elephant Snot® with extra dwell time (30 - 40 minutes) should work quite well. Use hot water, if possible, at 1000 psi. An application of Shadow Max® may be necessary. A note of caution -- many stucco surfaces are not the original colored dash coat. If the stucco is painted, it is best to simply repaint.