Absolutely true. Two merles bred together usually results in white, deaf and blind pups. I have a merle stud and if people want to use him on their merle bitch i refuse, i wouldn't chance it. I don't think there are breeders specifically breeding merles, but if one of the parents are merle then quite a few pups will be, well in my experience that's the case. I love merle colouring on a lurcher, especially blue merle, stunning.