Tags - ugly, angry, childish, and like crayon scrawl on the living room wall. Expensive for poor taxpayers, arrogant, stupid, pointless, an epitaph for the culturally dead and disenfranchised.
Permissions - interesting self expression and a legitimate art form.
Most graffiti is done by the desparate who have no other means to leave their mark on the physical world...it's like claw marks made by a drowning person on the piece of flotsam that they hoped would save them from drowning...but didn't.
Don't even know what the others are.
