I remember reading something about tagging subculture and while a lot of it was just a slightly older version of "Bob woz ere" there were some slightly braver/more stupid(?) individuals who were basically competing to see who could tag the most dangerous/obscure/hard to reach areas. From a purely artistic sense I generally find them really boring unless they're signing artwork and I get especially crotchety when losers tag over other people's work. I do like the "naive" style portrayed in your opening shot. Whoever did that gets more points for being socially responsible and not painting over the warning label.

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