[FBMike]

Aces-up probably won't win under normal circumstances, but you did open the door for non-normal circumstances with a check on the river. If you think a man off the street will bluff 1-time-in-7, you have to call. With an opponent who you might play with for many hours, this call should be automatic for many reasons (decent enough pot, seeing how an opponent plays, "image", etc.) The only real question is if you should raise, thereby giving you better chances to escape showing your halfway good hand in a somewhat dicey situation.