What breeds do you currently breed
A breeder should not be breeding more than 2-3 breeds of dog without a really good reason. The dog breeds need to be closely related in function and type (like a Cockapoo and a retriever for therapy work or malamutes and huskies for sledding dogs, or Border collies and Australian shepherds for agility, etc)
If a breeder has dogs that are all extremely popular breeds but are not related in function other than to produce an income buyer beware. That is not going to be a breeder you want to get a dog from. Remember that when the bottom line is the bottom line with any breeder you are not going to get a high quality animal and you’d likely be funding an irresponsible breeder who peddles heart-ache.
If a breeder has dogs that are all extremely popular breeds but are not related in function other than to produce an income buyer beware. That is not going to be a breeder you want to get a dog from. Remember that when the bottom line is the bottom line with any breeder you are not going to get a high quality animal and you’d likely be funding an irresponsible breeder who peddles heart-ache.
What (other) breeds have you bred in the past?
Steer clear of the breeder that switches dog breeds every couple of years, staying in trend with what happens to be the current fad in popularity. A breeder should be pretty well devoted to a specific dog or set of dogs and really shouldn't vary much from that at all.
How many dogs do you own?
There is no magic number here. As long they work and exercise all of them it is fine. It is hard to spend quality time with a large number of dogs so use this answer as just a piece of the bigger picture. An answer can be anywhere from 1 to 20 but if a breeder has more than 20 dogs (whether in guardian homes or not) run the other direction.