I think it is important for people to occasionally remember that the concept of what is "appropriate" is completely made up.

Stuck alone on Mars? I'd say that the "appropriate behavior" for that situation is pretty well undefined. It seems like a good opportunity for teachable moments: "Okay, Jenny, let's not use our Mars-language at the dinner table."

If the parents and other authority figures in the child's life aren't already providing good models of social behavior, then the kid's got bigger problems to worry about than the rough language in the book, and if they do have good models, then I don't see the problem, as long as the context gets explained to them at some point.

> Kids need models of appropriate behavior.

How about their parents? Should we change every book out there so it can be a children's role model now?

sure, but what does that have to do with swearing?