The bathroom in my apartment looked pretty gross. A non-zero portion of that was just because of the amount of stuff in the water. The other major contributor was the finish on the tub--it was scratched in a few places, and dirt would get into those and was next to impossible to get out through normal cleaning methods. I had to go in every so often with baking soda and dish soap and scrub them out.

The one time my sister visited me, I only had enough warning to clean the kitchen (white tile, so it showed dirt like nothing else). She has rather higher standards of cleanliness than DBF and I do, so I think she pitched a fit about it to our mom.