Here is where this affects you as a consumer. You select a painter with a contract that says 2 coats, $500 down. You give the company the deposit and pick your colors a couple of days before the project starts. The painter goes to the store with your colors and figures out they are deep base. He (or she) not only needs to charge you more for the paint, but he also needs to charge you for a dark gray primer coat. Ninety nine percent of the time that primer coat is going to be really, really expensive since you already gave a deposit.
Safest way to ensure that everything is fair is to get it ALL in writing , signed by both parties. Specify each item that needs repair. Also, BUY the paint YOURSELF. That way, there is no incentive to water it down, and you KNOW that you are getting the grade/quality you actually purchased. Don't be penny wise and pound foolish; if you are paying to hire a painter, buy the best paint that you can afford, to ensure maximum life of this home improvement.
First off, the picture on the top THAT IS A HOME OWNERS PAINT JOB. If you here a school kid or your neighbor, this is what you get. I was a painting contractor for the better part of 40 years and never saw a PAINTER (even the worst painter) leave a mess like that. Maybe the electrician or the carpenter but, that is not something a painter could even do if they tried. House Painting Westminster Colorado