That's why we can't assess a job just by the size of the space, we need to know how dirty it is, how careful the bricklayers and painters have been, whether it's just dusty or whether there are any plaster, paint or cement residues.
It's also very important to know the type of windows, whether there's a kitchen, whether the walls are tiled or painted, whether there's a built-in wardrobe, baseboards, lights, lamps, terraces, ceilings and especially the floor.