The place I work in is stripping and re-waxing the floor. Apparently this is done twice a year. Once in the summer and once during Christmas break. You don't really notice the grime until the stripping takes place and the new wax shines.
Another thing I've noticed is that the floor isn't mopped everyday so the dirt builds up fast. (Sort of like my kitchen floor, but we aren't going to talk about that now.) Maybe, like my soul, if it was scrubbed everyday it wouldn't take such drastic measures to keep it looking (or feeling) good.
Gunk On/Gunk Off