My children's stepsister told me her teacher said 'everyone is everyone's best friend'. If that was my kids teacher, I would want to throtttle her. Why set a child up for disappointment like that? I'm not saying to tell your kids that everyone is out to get them, but I think feeding them idealism like that is just setting them up for disaster.
Things I think children need to know (i'm kind of reiterating from a particularly disastrous thread that shall remain nameless):
-Everyone is worthy of your respect, until they do something to lose it.
-Everyone has the potential to be your friend.
-Not everyone is going to be your friend.
-Don't waste time on people who don't want to be your friend. Concentrate on treating well those who do.
-If you can walk away with your head high, then walk away.
-If you can't walk away, because someone is continuing to push you, then push back, with just enough force that they back off (I say this both figuratively and literally)
-Never throw the first punch.
-If you do, then you deserve whatever ass-kicking you receive.
-Know when to apologize
-Don't hold grudges. If someone wrongs you, let it go. Forgiveness takes less energy than hatred and vengeance.
-Forgiving doesn't mean forgetting. Just because you forgive someone wronging you, doesn't mean you have to give them the chance to do it again.
I think we as people don't give children enough credit for being able to handle simple truths. Although I don't believe in throwing children to the wolves, I do think that sheltering them incessantly from some of life's harsh realities only serves to do more harm than good in the long run.