There are a few main things are that are looked for when an eval is done.
Most reputable breeders will eval and put the pups in order accordingly after looking at these factors as related to the breed standard of the org the pup is registered with:
-working drive and ability
- overall health
A pup that meets the needs and expectations of their breeding program as a whole is usually deemed the pick pup. Pick of the litter means different things to different people.
The sex of the dog may or may not be a factor if there is a preference but not as to quality as a whole to which is actually the pick of the litter.
When you have bred a great litter picking becomes harder and harder as many may fit the bill.
Often I see kennels advertising show or working quality pups that are newly born which there is no way to tell if that will be the case so early. You certainly can't look at a couple of week old pup and know much of anything besides that it is cute and its color. You can of course also see if the pup has obvious issues like a tail is kinked, if it has cleft palate.
Color should not be the basis of making a pick. Of course it is OK to have preferences but the other things listed are what is much more important.
That is why first and most importantly the knowing standard inside and out, and the breeders experience overall with the breed and doing evals come into play a great deal when you are searching for an addition to your family.
Then evaluation tools such as Puppy Puzzle, Volhard Puppy Apt test etc are extremely useful so is just daily observations of the litter and individual pups.
Volhard Puppy Apt test
Volhard Puppy Aptitude Test
(I like to adapt this to my own needs and eval)
Dogfolk Enterprises - Videos, Books and Seminars for puppy evaluation and dog showing
After a proper eval is done it is easier for a breeder to help a potential new owner be matched to the right type of pup for them.
What the new owners are looking for in a pup ie. show working both or solely a pet needs to become a factor in placements. This helps to make for both a happy owner and happy pup. This is just one of the many reasons it is important to really get to know and trust the breeder you are dealing with when purchasing a pup.
Just sharing for those who are interested in Puppy Puzzle for evaluating puppies. It is a great tool that teaches you how to eval a litter more accurately
A pup at 8 weeks as long as they are not born premies, runts or have some other major health issue will pretty much give you a good idea of what the dogs adult structure will be; as seen in the below picts I took of Samurai who was a puppy out of my litter. Here is the day I did the eval and him as he matured. LOL almost the same pose too, what a brat
week 8 Oh mom, just give me the dang cookie this show stuff is making me hungry
Samurai the weekend he Championed... such a wiggle butt:
So as you see pups grow and change yet there are ways to sort of look into the future to help make better choices.
Of course no eval is foolproof but when looking for specific things in a new pup they are extremely useful.
Having a clear cut plan for exactly what you want and expect from your pup is a huge help when picking the right one for you and your family.
Hope that helps