One would think it's bad host etiquette to call your guest a goon.

Yet, David Letterman on Tuesday's "Late Show" did exactly that to Fox News's Bill O'Reilly.

He also told the "Factor" host, "You're too smart to believe what you say." 

All in all, it was a friendlier encounter than we've seen in the past with the following notable lowlights (video part I embedded right, part II below the fold):

• After O'Reilly gave his background before becoming the "Factor" host, Letterman responded, "When you say working your way up, does that really apply to Fox?"
• Holding up O'Reilly's best-selling book, Letterman chided, "Here's what breaks my heart about this: In my mind, I think of you as a goon! But then, when you look at, look at this picture, look at how sweet and adorable that kid is, and it breaks my heart because I have a sweet, adorable kid like that, and I think, 'Oh, great, what if he too becomes a goon?"
• When the discussion moved in the direction of whether or not Rush Limbaugh is now the head of the GOP, O'Reilly asked Letterman why he wanted that to be the case. Letterman responded: "Well, he's tubby. He's, he for a long time had his housekeeper buying illegal drugs. And I thought, 'Well, if this is what the Republican Party needs, there you go.'"
• Still on Limbaugh, Letterman said: "It just seems to me that he's too smart to believe what he's saying. And I feel the same way about you. You're too smart to believe what you say."
• When the discussion moved in the direction of former President George W. Bush, O'Reilly said, "Obviously, he presided over an economy that collapsed. That's on his sheet." Letterman quipped, "Presided or ignored?"

As the segment wound down, Letterman made a truly telling admission:

As ignorant as I am, and there are few people more ignorant than I am, I didn't, I didn't realize the deficit that this country had established for itself, or had been forced into for eight years until the previous tenant left the House...the state of the United States globally, until we got a guy in there who was actually, and who knows if he's doing the right thing, but at least he's doing something. But to me, the United States government was essentially closed for eight years.

Amazing. So, Letterman was oblivious to everything that occurred in Washington, D.C., until Obama was inaugurated? 

Tells you a lot, doesn't it?

—Noel Sheppard is the Associate Editor of NewsBusters. Follow him at Facebook and Twitter.