The attention of such persons, however, being always principally directed, not to the standard of ideal, but to that of ordinary perfection, they have little sense of their own weaknesses and imperfections; they have little modesty; are often assuming, arrogant, and presumptuous; great admirers of themselves, and great contemners of other people. Though their characters are in general much less correct, and their merit much inferior to that of the man of real and modest virtue; yet their excessive presumption, founded upon their own excessive self-admiration, dazzles the multitude, and often imposes even upon those who are much superior to the multitude. The frequent, and often wonderful, success of the most ignorant quacks and imposters, both civil and religious, sufficiently demonstrate how easily the multitude are imposed upon by the most extravagant and groundless pretensions.From The Theory of Moral Sentiments - Adam Smith (1759).
Further thoughts on the question from Mark Steyn: This job, too, is beneath Obama
I had intended to include a link to this excellent Dorothy Rabinowitz piece: The Alien in the White House