On the question of whether Donald Trump is a sinister mastermind or an incompetent scumbag (not mutually exclusive), last night’s debate will have to register in the scumbag column. His constant interruptions, vanity, self-pity and frequent forays into lies and nonsense are all by this point wearyingly familiar. Of course, Trump has been consistently underestimated since he entered politics, and his supporters no doubt enjoyed the petulant way he dominated proceedings. But his abuse of Biden was a far cry from the humiliations to which he subjected his opponents in the 2016 GOP primary debates. The show has gotten old.