One of the best ways of combating graffiti is to prevent it. By using sacrificial surfaces and keeping on top of maintenance, it’s not too hard to keep graffiti at bay. This works extremely well for surfaces that can’t simply be painted over. Commercial windows, stainless steel, mirrors, transportation windows, etc. are all examples that work best with these coatings. Places like walls might benefit from another type of maintenance. Some property owners are now allowing “safe spaces” in which artists paint murals over existing graffiti. These murals and street art are beautiful and actually liven up space. Some will go as far as having competitions each year and allowing the winner to paint a new mural. Could this be an answer for painted surfaces?
Source: Murals Conquering Graffiti