Imagine a world in which signs are obeyed.  My photo below is a glimpse of such a world.  The graffiti artist as well as would-be bill posters left the wall un-besmirched on this artfully-constructed wall. I guess the artist felt free to express him/herself on the federally-owned post office relay boxes.

Artful Barrier, Respectful Graffiti Artist

Or maybe I just got there early.