Some proposals simply say to paint the walls and ceiling and never specify the number of coats to be applied. If the colors are similar enough, it's possible to get away with one coat of paint and not discount your pricing. No matter how hard you try, tiny, pin-sized air holes will pop exposing the original walls. This may not bother you if you can't notice it, but principally speaking you should have paid your painter less for the work.
I'm hiring an interior painter and that is why I was reading this comment list. I'm concerned about your comment about Angie's List. Some of us don't have personal recommendations for tradespersons, and rely on sites like this. Are you saying that Angie's List's reviews are not complete or that they do not print some of the negative reviews? It's hard to know what to do - I have not been able to find a person who just had their paint done so I can ask him/her about the quality of the painter.
Thorough preparation is essential to ensure a good finish. Contractors might have to fill cracks or holes and remove old paint if it is badly worn, peeling or flaking. They remove all paint and apply a suitable primer to the bare surface. If the existing paint is in reasonable condition, they clean it and rub it with abrasive material to provide a key for the new paint. On new surfaces, such as bare wood or fresh plaster, they apply a suitable seal, followed by a primer coat.