From a judges perspective - the colors in the standard do not say 'prefered' Here is what the standard says:
"Coat and Color
Coat short and fine. Skin very pliant.
Color–Chestnut red; pure black; tricolor (pure black and chestnut red); or brindle (black stripes on a background of chestnut red); all with white feet, chest and tail tip. White legs, blaze and collar optional. The amount of white should never predominate over primary color. Color and markings should be rich, clear and well-defined, with a distinct line of demarcation between the black and red of tricolors and the stripes of brindles. " That seems pretty clear to me.
Now we all know there are variations - I have seen some very nice saddles and nice trindles - if they were in my ring - I would consider them BUT if 2 animals are equal in every way but one is a unique color- MOST judges will award the one that is closest to the standard in color.
The ONLY knowledge that most judges have - is what we as a parent club give them. If we want to amend the standard to say "preferred" we should present that option to the membership. If we want the "a good hound can't be a bad color" type of statement - we then need to present that option to the membership.
The way the standard is right now - if someone was a provisional judge and being observed by the AKC rep - and put up an odd color it would be considered against 'type' and that provisional would most likely get a bad review.
The AKC has alternate color options so that the paperwork most closely reflects what the dog looks like. In some breeds - an off color - is NOT registerable as per the parent club.
I personally am more concerned about the structure of the dog and the way that structure allows the dog to perform the functions for which it was bred. I doubt if prey cares if they are chased and run down by a blue, red or zebra stipe.
I just hate it - when I study any breed and standard when it doesn't reflect what is being presented. My Favorite was at a breed study when they handed out an illustrated standard and 15 judges were looking at it and they said, "Oh don't pay any attention to the picture on the cover - it's a famous dog from a long time ago but no one likes it and it's structure is all wrong." Now what use it that!