I think a little responsibility has to fall on the breeders who sell to unsuitable homes. For every litter I bet I turn down two or three enquiries for whatever reason I just know they won't cope.

Totally agree. Whenever we have bred a litter of collie pups (which are few and far between) we only sell to good working homes and I would only consider pet/sport homes that I knew personally to be excellent homes, suitable for one of our dogs.