I have said before that even if Rod Russell was a breeder, I would not just assume that based on what all he goes on about health (sorry Rod), I would still do dilligence and want to see certificates, parents, meet him etc.
The point of symptomatic CM cavaliers have been brought up that based on Charlie's scan alone he could be considered an "A". This topic has been talked about before and I don't want to go into all that, but at some point we have to trust the researchers, breeders, etc. amd go further and meet the parents etc.
So yes I agree with Margaret that you need to see the certificate but I would go further like you said Karlin and meet the breeder and parents face to face.