I've not had a problem with strangers commenting about my parenting skills when I am in public with my nine-year-old son with autism. I don't ever see any evil nor do I hear of any evil coming our way either.
It's not because my guy always exhibits perfect behavior. Believe me, he has had his moments. Further, the avoidance of angry stares and rude comments is not because I am the perfect mom who is always in total control of the situation. OK, once I lucked out and received kind, effective help from another autism mom who knew exactly what to do when a meltdown occurred in public three or four years ago. At that point of time I had no clue as to what to do because of a lack of experience. Back then, the main way of dealing was not taking the kid out. However, that is not a practical solution nor is it necessarily good to stash your kid away at all times.
Anyway, the reason I probably missed, stares, glares and comments (can't with certainty that we ever attracted such behavior) is because I have developed tunnel vision as a coping skill. I simply tune everyone else out and focus on my son when behaviors occur. I look and deal only with him (and his little brother. ) Maybe, when I do this I have the appearance of seeming in control. I don't know. What I do know is that narration also helps. Not so much for my son, but for the benefit of strangers. Here are some examples of some of my narrative statements:
"It's against the rules to run behind the cash register. That's a no, no!"
"It's the cashier's job to scan the items we are buying at the store."
"Yes, I know we have been to too many places and you are getting overwhelmed."
"Come on, let's go. You are acting really silly right now."
"Oh, no. Now I have to pay for those tic tacs because you opened them. But believe me you are not getting any more once I'm finished paying for these groceries!"
Back in the day when it was screaming and crying rather than inappropriate behavior it was:
"I know, I know you are not happy."
"We're going to have to leave right now because you are acting this way."
I'm not sure if tunnel vision accompanied with narration will work for other parents who have had to deal with a meltdown (tantrum) in public. However, it does seem to work for me. You cannot hear any evil when you are too busy making comments on top of what's coming out of your child's mouth. And you certainly cannot see any evil when you are focused entirely on your child (unless paying for groceries, etc.) Tunnel vision with effective narration may be worth a try...