
Although I dont breed I would suppose part of it is down to gut feeling .
Also finding out where the potential owners live , whether they have a garden etc , whether they are familiar wth the breed , have they owned before , are there children in the family and of what age etc etc
Some breeders say they will vet the house also to see its suitable .
If they are your puppies you have as much right as possible to ask as many questions as you like