I take an ecumenical approach to public art, and definitely include graffiti. There are large, complex installations around town that were obviously commissioned or at least allowed by the building owner, because they were obviously not put up quickly in the middle of the night. But there’s plenty of freelance tagging and the like, and not every building owner welcomes such contributions.
I played with filters to make the painted over graffiti a little more visible. This is on Dickerson Pike at Douglas Avenue, on the south side of a padlocked building across from Hester Battery Services.