First of all, people I just met on the street, I don't care if my dog is purebred. I don't care if you think she's thin. I don't care if you think she looks more like a Chihuahua than a Mini Pinscher.
I rescued her from an abusive family, I feed her three times a day, and I love and value her more than your opinion. Maybe next time you should reconsider being an asshole next time we meet.