I don't think it would really matter if it doesn't match factory. Who cares? I mean, if it's an old car and the paint is already oxidized and fading, then, repaint it by all means. It's an eyesore for crying out loud. I've seen really good paint job on an old car. But, I think it is good to avoid shops without a paint booth. You know, those guys painting by the roadside. Lol

Anyway, you can see samples of the finished product. On the spot, you are able to judge how good the paint job is. Best practice is to visit a few of them and decide.