One word: Spygate
Let me refresh everyone's memories. In 2007 the news broke that the Patriots had been secretly recording other teams signal calling, and then using that information in games. In short - they cheated and likely won games because of it. The Pat's lost a first round pick, got hit with a $250k fine, and Belichik got hit with a $500k fine.
How does this effect Payton Manning you ask?
Answer: If it wasn't for playoff loses to the Patriots in the 2003 and 2004, Peyton might have two more Super Bowl rings right now.
Don't think for one second that Peyton doesn't recognize that fact, or that he doesn't suspect those games were won by shady tactics.
Both of those games have one thing in common. The dominant Colts offense was surprisingly shut down by the New England Patriots. In one game Ty Law intercepted Peyton three times, just happening to magically know where the ball was going before it was thrown. Do you think he may have known something?
If not for a 24-14 loss in the 2003 AFC Championship game, the Colts would have gone on to play the Panthers in the Super Bowl, and likely won a ring.
Peyton's legacy forever changed after those games. I wonder myself if the Pats cheated in those games, and if they hadn't would Peyton have two more rings? If I wonder about it, can you tell me it never crossed Peyton's mind?
GM for those games: Scott Pioli
Defensive Coordinator for those games: Romeo Crennel
Peyton never sniffed the Chiefs because he would never go to a team that had a coach and GM who he suspected of stealing two playoff games, and possibly two Super Bowls.
That's my theory at least. Feel free to disagree. If this has been discussed before on AP I apologize. I don't read all the fan posts or comments.