In an interview with David Letterman on Wednesday night, Letterman picked up where traditional journalists left off, posing a patently ridiculous questions about the lipstick cliche:

Letterman: Let me ask you a question here: Have you ever actually put lipstick on pig?

Obama: The answer would be no. But I think it might be fun to try …. This is sorta silly season in politics. Not that there’s a non-silly season, but it gets sillier. It’s a common expression in at least Illinois. I don’t know about in NYC. I don’t know what you put lipstick on here. (laughter) In Illinois, the expression connotes the idea that if you have a bad idea — in this case I was talking about McCain’s economic plans — calling them change, calling them something different doesn’t make them better. Hence lipstick on a pig is still a pig.

Keep in mind, that technically had I meant it this way, she would be the lipstick … The policies of John Mccain would be the pig.

I actually heard a reporter offer this same deconstruction of the analogy on the bus yesterday. But it’s pretty low on the list of reasons why this false attack should never have been seriously covered in the first place.

The real joke, as Obama might say, is on the American people.

Obama has a major TV booking most nights this week.

On Monday, he did Keith Olbermann‘s popular MSNBC program, “Countdown.” On Wednesday, he’ll chat with David Letterman. For the second straight week, Obama is also a recurring face on Bill O’Reilly’s program. “The Factor” host keeps parceling out clips of their Republican National Convention interview.

Some Democrats criticized the Fox gambit, since it boosts O’Reilly and may do nothing for Obama, given that the audience is primarily made up of Republican senior citizens. As “O Force One” flew over Michigan on Monday, I raised that idea with Robert Gibbs, Obama’s communications strategist. He emphasized that, regardless of the media outlet, the goal is simply to get Obama’s message out during this critical phase of the campaign.

Jen Psaki, a traveling spokesperson for the senator, added that the media outreach complimented Obama’s political orientation. “This campaign has never been about speaking to just one wing of the party. We have visited parts of the country where Democrats have never been, and we are competing in parts of the country where Democrats have never competed,” she said. “Speaking to an audience that isn’t necessarily our base is par for the course — and part of the reason why Republicans and independents are taking a close look at Barack Obama,” Psaki added.

This outreach makes sense. Maybe Obama can pick off a few stray Republicans.

At a minimum, he might get more street cred with independents beyond O’Reilly’s base, if they think he proved his mettle under pressure. The hidden cost, however, is empowering O’Reilly to frame the debate.

I was reminded of that problem today during Obama’s press conference. The first question pressed Obama on his favorable remarks about the surge, from one of his feisty exchanges with O’Reilly. The real challenge, apparently, is winning over O’Reilly’s viewers without sounding like their hero.