Hospital floors are disgusting

Right close to the wall, the floor in the Emergency and Observation areas looks okay.  And around the beds, where there's a lot of wear from the beds being shifted, the floor looks fairly clean.  In between, it's grungy.  Incredibly greyish grotty.

I know the floors are washed, sort-of.  I've seen people pushing around some kind of antiseptic mop/brush/swab thing.  But it's not taking the crud away.  If I squirt a bit of hand sanitizer on the floor, wait a few seconds, then rub with a tissue, the floor gets back to the appearance of the clean areas.  And the tissue turns dark grey.

The old line about "but it's clean dirt" I find unconvincing, under the circumstances.