The typical Bad Cat Breeder is someone who knowingly sells kittens that are sick, suffering from common parasites and diseases such as Calici. They are easy to spot because their kittens look diseased, malnourished and neglected.
There is an ever-growing contingent of Bad Cat Breeders that are very difficult to identify. Their breeding cats appear to be very well taken care of and very healthy. The breeder boasts show win after show win, top breeding lines and offers only the best of the best. Interestingly enough, these breeders often have a strict "no visit" policy citing "threat of disease brought in from the outside" as a reason. If more than one red flag goes up - you are most likely looking at a sophisticated version of a Bad Cat Breeder.
Only if things go wrong will you see who this breeder really is. Communication often comes to a screeching halt. The breeder will accuse the buyer of wrong doing. The breeder will insist on a costly necropsy even in the face of veterinary documents clearly diagnosing the pet with a genetic defect. The breeder will offer no refund, no replacement or worse - threaten the buyer with legal actions if they do not "stop the slander".