The DM isn't controlling the players. The player of the paladin is choosing to use sense motive against my bluff checks.
Again, any circumstancial penalties or bonuses that are not inherent on your sheet are typically given by the DM. Such as you entering a room that has some kind of field or obstacle that imposes a penalty or confers a buff. It does not mean that a player can say "I have a super high iron will and so I get a +40 to any mind affecting spells!"