There can be no doubt that keeping all the pups, and "looking at them and seeing what you've got," as adults, is the surest way to find out what you have. (I don't think anyone could argue with this position.)

However, the question centered around the idea of selling a few pups, while keeping a few for oneself, and the gist of the question was trying to use color as a criterion for selecting the best individuals. And, IMO, as someone who has sold a lot of dogs, and made decisions for over 23 years as to "which ones to keep," and have been able to keep my dogs competitive with the best in the world by breeding those pups I kept, I think color very oftentimes does play a part in my selection process. But not always! So I would never select a pup just based on color alone.

I also look for other characteristics that I value (intelligence, intensity, apparent speed/athleticism, movement, etc.). So while color is not my primary motivating force in selecting a pup, if a given individual has the color of the key dog it is linebred on, and if it also exhibits "the look in the eye," the attitude, the speed/athleticism/movement, and the other characteristics I see (or remember) about the very key dog that pup is linebred on, then I am pretty freakin' sure that this pup stands the best chance in the litter of being "what I wanted" when I made that breeding ... and I am very seldom wrong in my selection process this way.

That said, I do agree that an ultimate "look" at the adult animal is the only way to know for sure.

Jack