Rudy Giuliani
Rudy Giuliani (Image: Getty)

Of all the grifters and cranks to attach themselves to outgoing President Donald Trump's traveling circus, perhaps the one with the most to lose -- apart from Ben Carson -- is Rudy Giuliani.

He could easily have gone down in history as an overzealous US attorney who took on the mafia and patented the "perp walk", or as a fantastically overrated New York mayor, largely on account of the fact he happened to hold the office on September 11 2001, and gave the public the hard-line response it wanted.

Now, after two years as turning up as a crazed and incoherent defender of Trump across the media (and even more humiliatingly in the latest Borat movie) Giuliani is a walking punchline. And he's learning what everyone who works with Trump eventually learns -- the president is petty, can't regulate his emotions and doesn't pay his bills.