Sometimes it is nessasary if the child is hurting someones feelings. Sometimes you just need to talk to the parents. We have a child in our neighborhood who is a bully and had NO manners and I have had to speak up a couple times.
Yes, I do but I think it should be done in a proper way. I wouldn't be yelling at or be condescending to someone else's kid, it would have to be done in a respectful way. I would also hope that someone would properly correct my DD if she needed it and I wasn't there.