I know that sort of thing can be frustrating. I get it all the time around the town anytime I take my pup anywhere. The "he's going to turn on you" and "no matter how nice he acts, he's just waiting to bite". It makes me want to scream sometimes. But the best thing you can do is focus on your dog. Keep working her so you can rub her excellent behavior in their face anytime they want to say something!
I'm not above calling my dog to a snappy heel when a stranger's made a snide comment, asking them to leave, and telling Kaiju to wave goodbye to them. The look on their face when he actually waves is pretty priceless.