A Note On Smooth Finishes
With the increasing popularity of smooth finished walls, we feel it's necessary to temper expectations about what you're getting when you pay for this option.
The standard level of finish before texture is applied (sometimes called a Level 3 finish) involves coating each joint, nails, and screws with two coats of drywall mud, and then sanding it smooth before texture.
Instead of texture, a smooth finish (called Level 5) is three coats of drywall mud at joints, nails, and screws, and then a thin skim of drywall mud over the entire surface of the wall or ceiling. This is meant to provide a smooth surface with minimal stipple. People choose this option when they want no noticeable texture on their walls, but it comes at greater cost and with some significant drawbacks.
Because the entire surface of the wall or ceiling has to be coated with drywall mud, it is almost impossible to patch or repair this level of finish without skimming the entire surface again. Changes made late in the construction process (relocating outlets, lights, etc.) become a headache when the walls are finished smooth; not only does the whole wall need to be re-skimmed, it will also have to be re-painted. This is expensive and time consuming, and would apply any time the wall needs to be repaired (whether during construction or years later).
There are factors beyond the control of the drywall contractor or painter that will affect walls and ceilings. Lighting conditions play a large role; no amount of careful scrutiny on the part of the drywall installer can account for all lighting conditions. No framing is perfect to begin with, and timber shrinkage over time will have a noticeable effect on finished drywall. The natural settling of a house as it ages will cause cracks and nail pops that are more noticeable when you choose a smooth finish.
What a Smooth Finish is Not
A level 5 finish can be an attractive option if you don't like the look of standard textures, but it's still only drywall. If you want your walls to look like polished glass or marble, this is not the option for you; drywall mud is not a cheap alternative to Venetian plaster or other decorative finishes.