There are a few key things to look for when trying to determine if a Labrador Retriever breeder is reputable. Some of the most important things to consider include:

1. The breeder’s commitment to genetic testing: Reputable breeders will have their dogs tested for genetic conditions that are common in the breed, such as hip dysplasia, to ensure that they are not passing on any known health problems to their puppies.
2. The breeder’s willingness to show you the puppies’ living conditions: A reputable breeder will be happy to let you see where the puppies are raised and will be able to tell you about the care they have received.
3. The breeder’s willingness to provide references: A reputable breeder will be able to provide you with references from other families who have adopted puppies from them.
4. The breeder’s knowledge of the breed: A reputable breeder will be able to answer your questions about the breed and will be able to give you advice on how to care for your new puppy.
5. The breeder’s breeding program: Reputable breeders will be selective about which dogs they breed, and will focus on producing healthy, well-tempered puppies that conform to the breed standard.
6. The breeder’s willingness to take the dog back: Reputable breeders will have a policy in place to take the dog back, at any time of the dog’s life, if you can’t keep it anymore.
7. The breeder’s reputation on kennel clubs, breed-specific organizations and online communities: They are often good resource to check the reputation of a breeder.

It’s also worth noting that there may be no guarantees that a breeder will be 100% reputable, so it’s important to be vigilant and do your research.