Between Jack Nicholson's 1989 portrayal of the Joker in "Batman" and Heath Ledger's 2008 characterization in "The Dark Knight," something sinister happened to the villain's iconic makeup. What had been a mask, with the clearly delineated lines of a carnival character, became simply war paint, and not very well applied.

The visual change signaled a change in the Joker's inner mechanism. Nicholson's dandified virtuoso of violence was replaced by a darker, more unpredictable and psychotic figure. What had been a caricature became more real and threatening. An urbane mocker of civilized values became simply a deformed product of urban violence.

It is the latter makeup job that has been superimposed over the face of President Obama in an anonymous Los...