The other difficult part is getting a painting contractor to show up. While this generalization does not apply to every painter, personally I am extremely grateful if I can get a paint contractor to show up to look at the house and to later produce a written estimate. I hardly fault the painting contractors, because I think it is a combination of the contractors being smaller operations along with a high demand for their work.
As you walk through your lighted rooms (preferably day light) see if the new coat has light spots showing the precious paint. This is call "bleeding through". This means that there's only one coat of paint or the paint was diluted or the trasition of colors were from light to dark (or the other way around) and primer was not use or the painter is inexperienced.
I agree with JHs. If there is no new color on it at all, just talk to the painter about it, if it was an honest mistake (which can happen very easily while painting) your painter should have no problem fixing it. However, in my years of experience, it is not unusual for 2 coats of door paint (good quality) not to cover very well at all. I once painted a red door 7 times, plus a tinted prime coat before I found the door to be a solid color.
The speed with which a painter can complete the job will determine its final cost, but time is difficult to estimate. Some painters have more experience and cover a wall faster, but some are more methodical and take more time. Most painters should be able to cover about 100 to 120 square feet of flat surface in an hour, unless they are working on a very large wall. Wood or plaster might reduce that amount to 80 to 100 square feet. You should also consider the time required for a first coat to dry before a second coat may be applied. This will add time as well -- anywhere from one to 48 hours depending on the paint.
Generally, it will take a minimum of two gallons of paint to cover a room. At the highest end, paint will cost anywhere between $30 and $60 per gallon and come in three different finishes: flat, semi-gloss or high-gloss. Flat finishes are the least shiny and are best suited for areas requiring frequent cleaning. Semi-gloss finishes are a bit shiny but can also be easily cleaned. A high-gloss finish is stain-resistant and easy to clean. Traditionally, living rooms should be painted with a flat finish to allow the paint to stand out. Glossy finishes should be reserved for hallways, and a semi-gloss is best suited for trim. Invest in pre-primed paint whenever possible. This cuts down on time by combining the layering process. Almost any paint job will require a primer, which will cost anywhere from $7 to $15 per can. Primer helps the paint to stand out against the underlayer of paint it's covering, especially if the new paint is lighter than the old coat. You will need at least two cans of primer, if not more, to cover one wall. Here are some paint brands and their average price per gallon: