My buddy's 8 year old daughter told me last week that she doesn't trust adults who smile too much without showing their teeth. She said it means they're hiding something. Kids pick up on stuff like that because they haven't learned to ignore their gut feelings yet. Adults are constantly second guessing themselves, but a kid will just tell you your haircut looks weird or that your fake laugh sounds like a dying whale. That kind of honesty is pretty rare once you grow up and start caring about being polite all the time. So yeah, I think the original point has some weight to it.