Good stuff. I think you could consider all graffiti art... that doesn't mean all graffiti is good art.... the same as anyone attempting to control sound could be considered music... that doesn't mean it is good music.
However, it can still be art, and still be vandalism at the same time if it defaced property belonging to someone else.
It can still look incredible doing such.
I'm not a fan of gang tagging.
Thank you for your answer! It is a good point about vandalism. As I mentioned, graffiti is more free, but its freedom ends, when it disturbs someone else's freedom.