Pastors are people. People are imperfect.
are PK's any worse behaved than other kids? is it just that we watch them more closely? does the PK try to counter the Pastor's rhetoric with tricks and games to put their parents to the test?
the most effective pastors I've known, are the ones who don't take themselves too seriously. they don't claim to have all the answers, but they're more than willing to teach you what they've learned.
Maybe once they get all puffed up, God allows their kids to behave in such a way that it helps deflate the Pastor.....