go to
www.bbb.com put in your zip code and then search for a particular business by typing in their phone number. You will be able to see how many complaints they have had in the past 36 months and if they are resolved.All companies ( even home depot) subcontracts out most of their work. I guess the most important thing to shop for is warranty of work,proof of insurance ( see the paper with your eyes), a firm quote (not an estimate-they are different) ,signed contract before work begins and discussion of handling damage and unexpected findings .