I guess I feel a little differently about this issue. I think that its cool that people express interest in your dog, so who cares if they don't quite know the breed? My dog IS a mix, so its kind of fun to hear what people's guesses are. They usually get the Chow part right. And hey, maybe they're right on any of their other guesses. After all, Cabeza's breed is only a guess on my part, too.
I guess what I'm saying is don't be annoyed...peop le think your dog is cool and want to talk to you about him! Think of it as an opportunity to be an ambassador for the Newfoundland breed! You can say, "oh! No! He's a Landseer Newf! They're named for the painter that used to paint them...they come from Canada and were trained to rescue fishermen out of arctic, frigid, water!" You know...whateve r. Then next time that person sees a Newf, they'll be SO PROUD of themselves for recognizing the breed!