Karl, I will make an attempt to answer your question with this posting. Collectors basically can be divided into two groups: those who are generalists and there are the specialists. Among the latter you will encounter Colt, Winchester, European, Kentucky, Military collectors, et al who oftentimes pare down their interests into unbelievable increments. And, they spend huge sums to get the best.
Without getting into further descriptions of those who may collect only mint Winchesters, Colts, or whatever, each group seem to have its own standards: e.g. serious Colt collectors will not give any consideration to a gun that has had any restoration whatsoever, including a replaced screw, grips, restored barrel, mixed numbers or any refinishing. Same with the Winchester/Henry folks. Of course it is not too hard to see how counterfeits have appeared which are perfect to supply the demand. The Military collectors are much the same: no restocks, no fore stock replacement, no reconversions, or refinishing. Pretty exacting standards!
The Kentucky collectors are pretty much a different lot. The Kentucky of legend was made during difficult times and most were used hard and put away dirty. Many were used in the westward movment and sad to say, most appear today as though they had been dragged behind the Connestoga wagon, rather than riding in it. You find all kinds of 'alterations and abberations' in them; barrels cut down, conversion to percussion, silver inlays missing, broken stocks, missing wood, and on, and on. So, finding a truly good piece is not as easy as going into the gun shop and buying a Glock. Good, fully original Ky Rifles tend to be quite scarce; not that they aren't around, they are. You just have to be there when one becomes available and have the where with all to acquire it.
There is a fair supply of the 'hurt' pieces needing work though, and this is where less demanding collectors can get into the game. Attend gun shows, estate sales, auctions, junk shops, or any other sales venues where old things are available. Something will show up. If this happens in San Diego, believe me when I say that you can depend that it will in your area. So. Cal is Colt and Winchester Country and very few KY Rifle came through, but still and all, they do show up infrequently.
So, collectors came to the position that a good rifle if in terrible condition can be brought back with careful effort it would be worth having. The first attempt seemed to involve reconversions and Keith Neubauer was one of the pioneers in ensuring that the new parts fit the time period and the style that worked with a particular gun. He went on from there to repairing broken stocks, adding missing wood, inlays and 'stretching' barrels and fore stocks. The results convinced collectors that restoration was a pretty good idea after all. In fact, many great guns have come back into the fold as a result of the efforts of superb artisans we have with us today. To name a few, Louie Parker, John (jtr), Jack Brooks, Brian LaMaster, and there are others as well who do what often seems to be a miracle with wood and metal to bring a badly treated, but good gun back. A well restored gun should look like it has had nothing done to it at all. There should be no mark that betrays the modern hand. It is possible to bring back a good aged appearance as well, but those processes seem to be closely guarded trade secrets. To maintain honesty, all restoration work records should be revealed at time of sale.
I know that this has run on somewhat, but it is kind of a loose history of collecting as I lived it, and recall it today. I know many collectors of Kentucky Rifles and no one I know turns a well restored gun away. Prices may fluctuate a bit between pristine pieces and those having some restoration, but that is reasonable. The pristing gun is one which is in the 'black, attic, or closet' condition, showing that long term storage by virtue of its surface color. Hence, 'in the black'. A gun from the safe or wall rack rubbed down occasionally over the decades will lack the dirt, but will nonetheless retain a smooth patina or mellow color that is not shiny, or which has noticable highlights. The stock will have color, or may even be dry looking. The silver will have likely have a dull appearance. To maintain this, I lay down a single coat of good cabinet maker's wax on metal and wood to avoid fingerprinting, or moisture and that seems to work fine.
As I said earlier, the collectors I know, and I do know a bunch, like to find that untouched gem and they prize its condition very highly. Guess that when the subject of this discussion showed up, it sped up a lot of pulse rates among those who would have liked to own it as well. Then, when it comes back as a cleaned gun and that done in what seems to a hap-hazard manner, it certainly attracted everyone's attention. Sorry that VT found the reactions not to his liking, but he still owns what is a fine, fine rifle and to be frank, the patina is not all gone and will come back over time, or can be repaired by one of the great restorers. I think that we were all in shock over it, and based our comments on that. I do hope that he forgives us and stays in the ranks.
Sorry to run on here, but I tend to do that. Thought that these reflections might be of interest to some of you. Karl, hope that this answers your basic question.
Dick