So you're cool with it if I create some "guerilla[sic] art" on your car or the side of your house? You're okay with it if I "decorate" a parking sign so that it can no longer be read? You've got no problem with it if I decide that I know better than anyone what aesthetics should prevail in the public space, and impose my tastes on everyone else? You've got no problem with it if I place my "art" on a wall that other people thought was just fine the way it was? How about if I decide to bonsai all the trees in the Public Garden?