Three referrals should be enough to assess the quality of work as well as the communication skills of the painter. Ask about the overall quality of the work, the work style of the painter, how the work has held up over time, and if they would hire him or her again. Be wary of any professional that refuses to give you references; a quality painter should be happy to have to speak to past clients.
I disagree with your criteria to hire a painter. A prompt returned call is nice but does not indicate the quality or fairness of the painter. As far as a written estimate, that should be more of a qualifier for the bid versus an evaluation criterion. I'm not sure one would have favorable results by hiring a painter on this basis. As far as the bidding process, change orders should ONLY be used if the customer requests additional scope (PMP 101). Angie's list should consider asking reviewers if/how much they were told to pay compared with the estimate. Unfortunately, there are a lot of contractors that are unethical and need to be accountable.
Only a dummy gets involved with so-called "contractors." Hire a qualified actual worker yourself. Check out their resume/background, etc. RULE #1..NO ADVANCE DEPOSITS! Pay daily or weekly or upon satisfied completion according your standard, not workers. Contractors are merely employment agents. If that's the way you get work done, then go ahead and waste your money and wind up with the myriad of problems enumerated upon in the news clip above. RULE#2.. NO SMOKERS. They are lighting up on your money. RULE#3: No cell phones while working. Talk on their own time after work
When the homeowner is at the point of hiring a painter, they generally will have colors selected or at the very least a color in mind. I always ask for the colors before I bid a job. Dark colors, high sheen colors and specialty finishes require more labor, this drives price. If its not a color change or I'm going over a similar color I give the pricing option of one or two coats. The best advise I can give based on 25 years in the business is to put it all in writing,colors, brands of paint preferred, when the work can be done, who moves furniture and how payment will be handled. I never get up front money. BTW you most definitely get what you pay for with paint. Higher quality products results in and better looking job. Don't be a cheapskate when it comes to paint or the painting contractor.
Beginning with the prep work and ending with last coat of paint or the finishing, an exterior paint job will last anywhere from one to two weeks. After completion, homeowners using low-quality paint will need to repaint every four or five years to keep it well maintained; homeowners using high-quality paint can go longer without a new coat -- usually about seven or eight years, depending on the type of paint and material.