Australis - Thats why a certification system is needed - If the animal isnt certified, then it cant be claimed to be a pure anything...Sure, it may look like a coastal / whatever, but everyone will know it isnt, because it doesnt have the surety of certification...Yes, certification would probably be expensive, however I believe that given the amount of money being handed over for animals at the moment, a breeder wouldnt be too put out in paying a bit extra to be 100% sure that they are getting what they are paying for (which is the beginning of a whole other discussion about so-called hybrids and why they exist)...
junglepython2 - Selling through the pet stores isnt something that would be effective on its own - It is something that must be done in conjunction with having some form of national breeders association and additional guidelines to only allow such members access to selling their animals through / to pet stores (ie, on top of that)...Obviously for it to work it would also require significant policing (at least initially - Once the association is properly recognised and seen to take effective action, the level of policing required would decrease)...
boa - Relying on the word of breeders as to purity of stock is insane, as you have already mentioned...There are, however, recognised traits, DNA samples and methods of identifying distinct sub-species scientifically, which is what would need to be used to independantly verify pure-bred animals...If a sub-species can only be identified through lineage and not through any other recognised scientific method, then such a sub-species is obviously not a real classification and should be dissolved back into the parent species...
The situation simply cannot be left the way it is at the moment, for obvious reasons...