"WRT graffiti, often (but unfortunately not always), historic buildings are left untouched as an unwritten rule and the ugly buildings gets sprayed (but again there are too many punks who don't get it)."
Have you seen the roof lines, doorways, walls, and other parts of most of the historic commercial building stock along Spadina, Queen, Bloor, Yonge, College, etc. recently? Pretty much every one of them is covered in tags to the point where I'm not sure many of those buildings are salvageable given their age and fragility. It's illegal vandalism that is slowly destroying a lot of the historic commercial building stock in this city, and I find it's the newer buildings that are maintained more vigilantly against this kind of thing. It's not that they don't "get it", it's that they're assholes who don't give a shit about anyone other than themselves. *They're* the enemy of heritage preservation to say nothing of the public realm as a whole, so tolerating it is not - architecturally speaking - shooting yourself in the foot, it's shooting yourself in the mouth.
As for postering, the vast, *vast* majority of postering is of the large-scale, Guvernment nightclub and Booty Camp variety, and *not* the mythical struggling young band variety. And it is for this reason why, thankfully, it is finally beginning to be addressed.
I really don't know where your perceptions arise from as they have no relation to reality whatsoever.