Hypocrisy has often been claimed to be the worse crime, that is the reason that conservative politicians who do immoral things are treated worse

So what about David Letterman? A list of politicians Letterman has attacked for sexual missteps includes:

Gov. Eliot Spitzer
Sen. David Vitter
Sen. Gary Hart
Gov. Mark Sanford
former presidential candidate and Senator John Edwards
Congressman Mark Foley

From Fox News:

Turns out David Letterman doesn't just live on a TV show. He also lives in a glass house, where for years he's hurled comedy zingers at misbehaving politicians, even as he brashly engaged in hanky-panky of his own.

In March 2008, Letterman was taking potshots at Eliot Spitzer, then governor of New York, who was embroiled in an investigation into a high-end prostitution ring.

"It's so sunny and bright outside that, earlier today, Eliot Spitzer came out of a brothel squinting," Letterman cracked in a monologue.

But in Spitzer's case, he didn't stop at lampooning. During an indignant rant, he called for the scandalized governor to step down.

"I mean, can you imagine," said Letterman, "if this happened to me how fast they'd have my ... (backside) out of here?"

Unlike Spitzer, who resigned, Letterman seems secure in his job as host of CBS' "Late Show," nearly a week after his bombshell revelations of having had sex with women on his staff (a disclosure prompted by an alleged $2 million blackmail threat against him).

But in light of his acknowledging past "creepy" behavior, it's kind of creepy to revisit a joke such as this one from a March 2008 show: "Let me ask you a question. Do you think it's too soon to be hitting on Mrs. Eliot Spitzer?" . . .

UPDATE: Here is an interesting discussion on Letterman from the UK Daily Mail.

Oooh, I enjoyed seeing David Letterman squirm as he confessed, on air, to having had sex with young women on the staff of his late-night chat show. This is the man, remember, who made a career out of lambasting Bill Clinton.
Two memorable examples spring to mind: ‘Now we hear that Monica has sued the President for $1,000,002.50. That’s one million for pain and suffering and $2.50 for dry cleaning.’
And: ‘I really have to hand it to the White House. Around here we can’t even get the interns to work the copy machine.’
Letterman’s confession was prompted by an extortion attempt, and although he admitted his actions had been ‘creepy’, his whole stance smacked of victim-hood. Had he really done anything wrong?
The four young women, one of whom would become his wife, were, after all, willing participants in the affairs. . . . Two of these women were in their 20s. . . .
Stephanie Birkitt, his former lover and assistant, had described herself as Letterman’s best friend. . . . ‘[Birkitt] was not punished but rewarded with a recurring on-air starring role, despite the fact that she wasn’t funny or charming.’ Miaow! . . .
And what about the other women who were passed over for ‘on-air starring roles’ because they refused his advances, or weren’t considered young and pliable and attractive enough? . . .

Apparently, Letterman was more recently than thought still having an affair with one of his staffers. The person who tried to blackmail Letterman was supposedly upset because his girl friend was still in love with Letterman. It isn't obvious from this how recently Letterman was still seeing this woman.