Quality is so much more than just how does it look the day it is finished. For a quality long lasting job a painter takes into account how to paint with proper application methods and materials that won't fail in time or will be easily serviced in the future, such as Painting a ceiling can be just sprayed on or backrolled (rolling the surface to; even out, work into pores, and give a stipple texture from the roller cover). The back rolling method is always better and often takes two workers to properly roll the surface. Now why is it so important that you buy this labor? Because if the ceiling in this case is only sprayed it will be impossible to touch it up without the ceiling looking patchy where it was touched up. where as for going with back rolling touching it up down the road will be as easy as pulling out a roller and painting the small area that needs to be touched up. Making it a prefered method in the end because it will be able to save you thousands of dollars and headache down the road.