Heard good reports from all mentioned.
I think two things to consider....
1) Inspect some of the work that they have in / just finished...have a good look at 3 or 4 cars.
2) Explain that you are extremely picky and you want a flawless job.

Everyone has their off days, but a respectable painter should be "man" enough to accept that their work wasnt quite up to standard and re-do it without question. We've had jobs we've ran out of time on, and gave the car back, wanting it back for more work free of charge. If you explain the standard you expect they'll know to do a good job the first time.