One of the most important criteria is that a reputable breeder does not have puppies all year round, but keeps a list of interested families for the next available litter. If puppies are available at all times this means they are shipped-in. These puppies are taken away from their mother at too early an age, shipped in terrible conditions, with no real proof of their genetic background. A big no-no. See also our complete checklist on How to identify a good dog breeder
Fortunately, due to the high cost of breeding and the small profit margin, commercial breeders usually stay out of the business of breeding bulldogs. However, this does not mean that all bulldog breeders are responsible breeders. Some may not be driven by the money but by the fame of breeding good show dogs which may lead them into unethical breeding practices, raising dogs with emphasis on physical conformation with the show standard, while neglecting good temperament and health.