To the sharp-eyed Shorpy viewers for noticing all the minute details of this photo, and that the building was indeed probably going through a renovation rather than just being a dirty old mess! I never caught all this until I read these astute observations.

The frequent affixing of adjectives like "squalid" or "reeking" or "crumbling" to the word tenement in contemporary news articles and essays reveals that the noun was not always a pejorative. Indeed, it refers to an arrangement of flats in a multi-storied building served by a central staircase, usually constructed with one or two walls in common with adjacent buildings. (The Romans had 'em; you can look it up!) Because it was a cheap and profitable way to provide housing for the many, and because "many" and "impecunious" are often closely associated, the "old law" tenement maximized density and minimized cost to the detriment of access to light and fresh air, resulting in a gradual acceptance of the term as the equivalent of "slum." Well, that and the presence of four generations in a one-bedroom, picking rags and praying for the Bronx.

This hallway view shows new construction. The wrought iron railing and stair stringers have not been painted yet and a scribed line in the plaster is visible about three feet above the floor where the separation of paint colors will be. A darker color below to hide scuffs and fingerprints.
No sense in mopping the floor until the painters have finished.

The wall at left seems to show evidence of plaster repairs to holes, and there's further evidence of plaster work at the top of the stairs. I think the two white circles on the hall floor are where buckets of plaster stood, and the nearer bucket got tipped over so that its contents ran along the floor.

Looks less like 'sloppy' than partway through renovations. The stuff on the floor could be old mastic.

Have these people never heard of a Mop?