I've come to feel that the phrase "of course" is just a warning that--perk up!--something is NOT "of course." Consider these examples:
NY Times: "There is of course a difference between speculative bubbles caused by greed and psychological ones born of fear."
NY Times: “Corporations are people, my friend,” Mr. Romney responded, as the hecklers shouted back, “No, they’re not!” “Of course they are,” Mr. Romney said, chuckling slightly.
I'm afraid that in neither of those cases is it obvious to me where truth resides. "Obviously" is another warning flag to me that something is NOT obvious. Does anybody feel the same way?