Still Graffiti, Still defacing a wall, Should be punished, Shouldnt be that dirty to start with, Not his job or right to mess with council property as he doesnt own it. Tricky case but basically he is defacing an area thats not his to deface.

Get a permit and do it under regulations, like a percentage of money goes to the council/whoever who have to agree to it first, then clean it off after a set period of time and use the rest to fund other clean-up operations... THEN its legal and beneficial to everyone.