I was refering to Anarchangel's interpretation above,
"If they fail, they must do what they were told."
That's why I would like to here concrete examples of how this went down in play, when someone refused a Parley, and how the "Defy Danger" went down in the game.
I can appreciate the idea of somehow factoring in your character's CHA in trying to influence another PC, but I think as written the move is vague and confusing, and can lead to undesirable side effects (meta-gaming, awarding XP for doing something against character, etc.)