I recently took my summer class to the Metropolitan Museum here in New York. When we stopped at this picture, there was some giggling, mainly because of the comical glasses. When I told them it was in all likelihood the Grand Inquisitor, it was suddenly viewed in a whole different light. Nobody expects the Spanish Inquisition.
I'm all for the primarily visual experience - it's the principle premise through which I make and talk about art. But it's undeniable that a small shred of non-aesthetic information can completely change the way you view a picture.