The first "quality" evaluation of a dog is in its pedigree.
Reasearch the pedigrees especially if they are not "homemade"*
The second "quality" is determined by his performance, structure, temperament, health tests.
There seem to be more and more aggressive dogs and we had been warned in 2005, by the then pdt of the club, about the increase of "barkers".
The third "quality" assessment is in its offspring.
By robbing the cradle more and more and using the same dogs several times in one year without waiting to see how the offsprings grow is suicidal for a rare breed= bottleneck on pedigrees.

In breeding an animal we concentrate on the good points and improving the weaknesses, but at the same time we magnify some problems both known and unknown. There is a time to sit back and watch what our dogs produce for more than the first generation....
This information was given to me by a breeder in the USA. It is the same as found all over the net, but people need to read it and not breed for convenience.

What happens to the race horses that are unsuccessful at the track?

This is all in responsible breeding and preserving the Barbet and making it strong and thrive.
Responsible breeding.

Quantity of pups, homogeneity,morphology once they have grown to adult size, color, coat texture, and of course are all the pups healthy? Character? Natural ability?
The reason for being of a breed.

This is not taking into account the price of services. Should they be the same as for a stud who has proved nothing?