This is why I am hesitant to even raise the topic...people so easily get bent out of shape on this subject. I think the general feeling is that it's fine to bring kids to watch if you don't mind that they may occasionally hear a curse word or see some adults drinking and generally having their guard down. Many of my Mommy Mafia-type friends would not be cool with it and would glare at people for cursing/drinking around the kids, but I don't think most people around here care...it's never out of hand.
The problem Sunday was that kids were playing, kids were standing at home plate when I crossed after running from first to home on a very sore leg, and kids heard me say d@mn and the f-word. This kid was pretty young, and it was pretty clear he found the words shocking. His eyes were like saucers. I felt so creepy after that. I am not a potty mouth, and the kid wouldn't have heard what I said had he been sitting where the spectators usually sit.
Now, I am not on the kickball board of directors, so I speak only for myself. My general feeling is that if you have a child it is your call to make the decision regarding what is or isn't appropriate for your child. If you don't mind an occasional d@mn or f#&# being muttered on a field, or a very genteel lady calling out, "That's two outs for the Large Nipples," then by all means bring the kids. Explain to the kids that it's a game for adults Tell them not to ask to play, and if they do ask don't leave someone else to be the heavy and say no. Kids are totally welcome to spectate. But, that's just me.