I recognize that all this graffiti is ugly and that it defaces public property in the most visible possible places, but what's not mentioned in these posts on graffiti is that the person doing it is not a criminal, vandal, or a thug, but a person with a very small intelligence.
Years ago the accepted terminology was "feeblemindedness," "idiocy," and "mental subnormality." These were replaced by the term "@#$%," which then became "differently abled." I'm not sure what the diagnosis is for such people today. However, this "graffiti" was created by one of those special people, somebody with the mental development of a toddler who scribbles on the bedroom wall using his mommy's lipstick and is now a more grown-up person who scrawls shapes and "words" on signs, walls, streets, and rocks.
We shouldn't condemn such people but offer them help in the form of special education.