I wonder is this also a metaphor for inner thoughts, and the scrubbing off the graffiti representing in wanting a change, a new start and struggle to overcome the depressing and dark thoughts that tend to always come back and hold on to you tightly, dragging you down no matter where you go every day.
I doubt that though. Seems pretty straight forward as something more dark. Positive outlooks and interpretations are too rare in most these cases.
