Most good breeders aren’t going to bash each other…but I wouldn’t consider what that breeder sent to you as bashing. The breeder is giving you what sounds to be an honest opinion about the sire. Not sure what the sire’s titles/accomplishments are…but in most cases, when an untitled dog gets sold/rehomed, it’s more for a negative reason than for a good one. Most breeders aren’t going to be selling their good stock to others when it could be used to breed.
A lot of breeders will not lie to potential owners, but they’ll embellish the truth. At the end of the day, 95% of buyers have no idea what they’re looking at. They see a nice, calm dog (sire/dam) maybe do a bit of obedience, maybe show some protection, and are very impressed. The breeder talks a little about what all that means, how their dogs are better than others, and they make a sale. Unless that dog ends up having huge temperament issues (uncontrolled aggression) or a terrible genetic disease of some sort…the buyer is going to be very happy. It doesn’t have to be the ultimate world champion working dog, it just has to be a good dog.