As almost everyone has said, it really can be both art and vandalism it just depends on the place it has been done and who owns the property. If the work has had some thought and effort into it, it's art, no matter if it's a stick-man with a stick sword. If that person thinks it's well done and put effort into it, it's art. Graffiti is no exception. If the graffiti drawn on a building "Kerry ♥ George 2k10" for example, and it not owned by the drawer then that is vandalism. If it's not yours, you have no right whatsoever to place your mark on another's property. But if it's on their own property, I don't see why they cannot decorate their building in graffiti, they own it after all.