I've had a few that stand out.
Twin boys, about 1.5 at the time, had always loved the bus, but this one day, for no particular reason had decided they HATED it, they screamed, I was frantically trying to placate them, there was no way I could get off I was miles away from where I needed to be.. Instead of dirty looks and tutting, two very nice old dears told me I was doing a wonderful job and made every effort to help me calm the boys down... It didn't work very well, but I appreciated the fact they tried.
We can't take DD (2) to a restaurant, it's more stress than it's worth at the moment, but we went out one evening when she was tiny, about 3 months. Just before dinner was served (as the waiter was bringing it over to us in fact) she threw up all down me (milk type sick, not poorly sick), I wiped it off as best I could, and sat to eat my meal, with baby on my lap. The boys were impeccable (they always are at restaurants at the risk of sounding smug) and a family on the table next to us commented how lovely it was to have sat next to us, the children were lovely and I had the patience of a saint not to be annoyed that my lovely new top was ruined... and I smelt of sour milk (I was annoyed, but determined to enjoy my first meal out in months, with friends that live so far away we only see them once or twice a year)
And the one that really sticks in my mind, when DD was 9 months we had tickets to see a pantomime with the boys (age 6) and our baby sitter for DD let us down, we ended up taking her with us (checking with the theatre first)
When we got there luckily we were right at the end of an row, and right by a door, so I sat at the edge, with DD on my lap, then the boys, then DH, next to him was a middle aged couple, who loudly tutted and gave us dirty looks when they saw DD. I was more than prepared to take her out if she started fussing, as was DH. I'd never have let her disturb others. DD LOVED the panto, she shouted in all the right places, laughing her head off, there was a bit with water guns being shot into the audience and she wanted more... She was an absolute angel tbh, and at the end, the woman of the couple asked to talk to us and apologised that she'd tutted at the beginning and that actually all three children were fantastic and DH and I were great parents. She told us to keep up the good work and that her and her DH had just loved watching DD bouncing and singing and how happy she was.
It made my day and I will never forget it.
I remember all the comments, because they were lovely, not patronising in the slightest. So many people are quick to complain about a 'naughty' child, but not to compliment a happy well behaved one!
I try to always make a point of telling children and their parents how impressed I am with their behaviour, and I do also try to help in some way with a child throwing a wobbly. Sometimes a kind strangers interaction can make all the difference with a bad day.