There are times when a slave should and will only be allowed to clean floors, on all fours, with a cloth or scrubbing brush and water. This slave is doing just that. The slave also knows that any moment its Master can come in and fuck its anus.
A dutiful slave is always available, knows no matter what it is doing the slave must stop the cleaning for instance, whenever the Master wants to use him for sex, or urinal, or just to cane him, then the slave gets back to work on his chores.
The best way for a slave to properly clean is on its knees, with a scrubbing brush, but the type of flooring dictates the best equipment. Solid ceramic tiles can be scrubbed, real wooden floors can be scrubbed. Other type of flooring a cloth or mop would be better.
Scrubbing like this is a good way for a slave to learn its craft.