Crossroads graffiti vandalized by mysterious advertising

Graffiti is obviously not discouraged in the alleys that branch northward from West 18th Street between Baltimore Avenue and Wyandotte Street. These walls have been splashed and coated again and again by spray-can artists (with varying degrees of talent) for a decade, at least.

Advertising agencies commonly co-opt street art for the commercial interests of their clients. Now, an ad has shown up on a wall typically reserved for street artists. The question is: What the hell is it for?