Graffiti can be destructive as well as constructive. How many times have we passed rail cars, an overcrossing, signs, etc. that have been painted over with the intention to vandalize? On the other hand, in blighted neighborhoods, graffiti can be used to coat a building with new life through color and contribute to improving the perceived quality of that neighborhood.
In recent excursions, I've had fun discovering some delightful art graffiti on buildings in unexpected places. Here are some photos of some of those places: