From my personal experience, I find that the proper calibration ( to industry standards) is well worth the investment. I see the difference in the displays from before and after the work. Mind you, that only with using the proper calibration equipment and software plus a tech that is trained in its use, will you get the best results. I speak of my girlfriends Elite plasma done with both day and night settings and what she thought was a good picture before the calibration, she was amazed with the after results. She had a Sony LCD done as well. and I know from watching it beforehand, the picture was just hard to take no matter what we tried. Now it is very pleasant to watch. On my own Sony 37" plasma that was done, I have had friends comment that it looked darker until I lowered the lights ( for the night setting) and they were impressed. I find it easier on my eyes, now that it is set correctly. The picture really pops out. Clear and crisp is how I can best describe it.
I can only guess that most people do not really understand what this calibration does for them, other than to be another expense. Very simply put, it sets the display to the same standard as to what all the production cameras, monitors and such are set to. This is how the movie is shot and viewed as how the director intended. And how you see it at a theatre. Those projectors/screens are all calibrated.
I know I said this before, but why would anyone pay for a service, if they are only going to screw it up after the tech leaves. Makes no sense. I know when I complete a job, I would not want the client to go behind me and undo, mess up my work(HVAC) because they think they know better. If that is the case, then why bother to have any work done in the first place?