Recently I was talking with someone looking for a fold and he asked about some of the "other" breeding practices out there meaning outcrosses. TICA and CFA (the 2 main registries in the US) allow for Scottish Folds to be bred to Scottish Straights, British Shorthairs and American Shorthairs. So kittens resulting from these "crosses" are considered Scottish Folds or Scottish Straights depending on what the ears do. These kittens are pedigreed cats and can be registered as such within these organizations, and most others around the world.
Which cross is better to use? To some degree this is a matter of opinion. Using the outcrosses of American Shorthair or British Shorthair you will loss some type, meaning the kittens will have some features of those breeds that may not be exactly what we are looking for in the fold standard. Some breeders feel that using these outcrosses will decrease the chance of OCD even more than if using a Scottish Fold to a Scottish Straight. Our breeding practice is we use Scottish Straights because we don't want to lose the look of the folds. There is now a DNA test that we have done on our breeding cats to make sure that our Scottish Straights do NOT carry the fold gene. As long as they do not, we feel we have the same risk of OCD as those using the outcrosses.
Now this particular person was asking about folds bred to other breeds such as a Persian, Himalayan, Selkirk Rex, Munchkins, etc. These are not allowable outcrosses in the cat fancy so any cats/kittens of these crosses are just Domestic Short/Longhairs, even if they have folded ears. People doing these crosses are not in it for the betterment of the breed and they are charging a lot of money for non-pedigreed cats. These "breeders" may even given them a cute name (think in the dog world all the doodles which are nothing more than mutts) so don't be fooled. They will not be able to be registered with either organization. They are just really expensive domestic cats!