Yes, I absolutely agree with that. "Which version would be right for the artistic vision" is the question. I'll try to answer both your questions like I see it:
For example, in our catalog you can find all studios that can send you a free preview sample of your track, mastered by this studio. Trying them for free you can find that maybe one of them is yours and understand better, what do you want and what you don't want about your song/track. Or you can understand, that online mastering is horseshit scam for you. =)
You want to master you new "country" album. You choose only studios that do mastering in this style. You're scrolling the list and you see that some of them also do mastering of heavy-metal and electronic. They're not yours. You haven't got a lot of money, so you're looking some middle-price studio. You need a free preview, like i said before. And you see all of it in one list - that's the idea. Then, when you have chosen for example three studios, you already trying to find a common language with them, sending emails or talking in skype, receiving your free samples, and so on. And then, maybe, you get what you need. If not, ok, you can try anything else.