Like a lot of you, there was a period there — 9/11 and for a month or three after — when I respected the hell out Rudy Giuliani. The respect ended faster and more thoroughly than my letdown over John McCain, a man who once either placed principles over politics or did a real good job of fooling me into thinking he did.
Giuliani went from being America's Mayor to being its screaming scold and there was a point there where he was pimping out his 9/11 cred as a spokesperson for anyone who'd pay him enough. In this past election, I don't think there was any vile rumor he would not spread about Hillary Clinton and so he did Donald Trump a big favor. Because of Giuliani, Trump wasn't the biggest, hysterical liar out there campaigning for Donald Trump.
There are reports that Giuliani went balls-out for Donald in an attempt to land the position of Secretary of State. Maybe so but it's now being reported that after initial reports that he was on a two-person short list, he's now out of consideration for that and apparently any cabinet post. He'd never make it through any confirmation hearing that examined his recent business dealings and the company he's kept, they say.
Why has he turned into what he's turned into? Michael Tomasky has a long profile/theory about Giuliani that sounds rather credible. You might want to give it a read.