Gatoreye- You will most certainly find someone who is unhappy out there. It will do well to understand the difference between science and preference, and where they both fit in a calibration. The first benefit of a calibration is the science. It is no secret that video display devices use a standard color of gray, that is 6500K. If this is the reference that they use when creating video, it is what we must use to accurately recreate it. Any divergence of this is not accurate regardless of someones individual tastes. To do this correctly it requires the proper equipment for that display, which is usually quite expensive. There are many other benefits that an experienced tech can offer, that can often produce an even bigger benefit, such as mechanical focusing.
Aside from these things that can be backed up quantitatively, there are other adjustments that are subjective. Many sets have a terrible color decoder, and as such, cannot be trusted by adjusting with a SMPTE color bar pattern and blue filter, like you find with Avia or video essentials. After ballparking it that way, it usually requires some good closeups of peoples faces to set the final color adjustment. So I will usually set this with input from the customer, but also offering my own experience as someone who has a lot of experience in looking at a reference picture. But in the end, the final few clicks can certainly vary from individual to individual, and even from TV channel to channel unfortunately. So you will most certainly hear of those that have continued to tweak the user settings in search of their own utopia, and I encourage it, knowing they can always return it to where we originally set it. These types of adjustments don't make much of a difference to the color temperature, as color temp is based on the gray scale, and adjusted via internal settings. As such, there is not much of an effect on color temp, regardless of their preference for the color introduction setting.
But in answer to your question,
The only time I have really heard of an UNhappy customer, was a situation where they had no idea of what it was, but they ordered one up anyway because they thought it would be magical. As it turns out, all they were hoping for was that some of the cable channels would come in better (less snow). They never bothered asking the calibrator what was involved, and the calibrator just assumed that the customer knew since the customer was the one inquiring. There is no magic, only science. Garbage in is garbage out.
Sorry to be so long winded, but I thought your post might elicit negative posts, and I wanted to qualify it.