So. After hours of scrubbing, the bathroom floor at the group home I work at is FINALLY clean. All the staff thought that the dark areas were part of the tile…nope, that’s built up dirt. Also, the one bright white line on the grout in the first picture is from a quick scrub with a magic eraser. No more swiffers for the bathroom floors here!
I cleaned it with elbow grease, a little scrub brush, soft scrub, and water. Nothing else but soft scrub worked…but it’s done!

(Wet Swiffers are the devil and worse than useless.)
This is why (re)sealing tile and grout is so important! I like this how-to:...
(Wet Swiffers are the devil and worse than useless.)