Sadly, it doesn't take much to be a registered breeder. All it really means is that the breeder is registering the kittens, which means the parents must also be registered and that the kittens are, therefore, actual pedigrees (many backyard breeders will use non pedigrees in their breeding cos they're cheaper and easier to get hold of but will still claim their kittens are pedigrees). So anyone can become a "registered breeder" and it doesn't mean they are a good breeder. Kittens are placed on either the active or non active register (I assume this is GCCF - I don't know much about the other registries). Only those placed on the active register can be legitimately bred from as kittens born to a cat on the non active register cannot be registered. A good breeder will be very careful to whom they sell a kitten on the active register to, regardless of the kitten's quality. Most will only sell to people they know, those who have demonstrated a committment to the breed by owning and showing a neuter or those who have been recommended to them by another breeder etc. That's the good breeders. The less scrupulous ones (of whom there are many) don't care who buys their kittens or are just not careful enough. It is certainly not good to advertise a cat in this way as being on the active register. If she is selling for legitimate reasons, she should neuter the cat first and transfer her to the non active register. Also, if the siamese is only 6 months old, she should be getting in touch with the breeder she bought her for as most will take back a kitten if the owner can no longer provide a suitable home. If the breeder can't or won't, she would be best off contacting a breed rescue. If she bred the cat herself, she needs to take a more responsible approach to rehoming. Either way, advertising the cat for general sale, and as active, is not the way to go about it. She may well be a registered breeder but she doesn't sound like a responsible one.