He sneaked a picture of the lapel of the official minder who had been assigned to watch him and a few other musicians.

Image Kim Il-sung is seen on lapels of officials in North Korea. Credit... David Finlayson

In North Korea, the Eternal President pin is a symptom of a national cult of personality, just as Mao pins once were in China; hammer and sickle pins were sported by many officials in the old Soviet Union, where an ideology became a political monoculture.

Here, the American flag pin is commonly held as a symbol of allegiance to a free society, not the emblem of a conformity that marginalizes dissent or writes it off as unpatriotic. Many right-wing commentators have toyed with Mr. Obama’s background, suggesting that he was reared in a fanatical Islamic religious setting (he attends a Christian church in Chicago) and have leaned hard on his middle name, which is Hussein. They have not complained that Senator John McCain doesn’t usually wear a flag pin.

And despite vacant lapel-age on Senator Hillary Rodham Clinton’s clothing, no one got around to asking her on Wednesday night why she wasn’t wearing a pin.

Instead, the other ABC moderator, George Stephanopoulos  like his colleague, Mr. Gibson, not wearing any visible flag pin  linked Mr. Obama’s empty lapels to the “general theme of patriotism in your relationships,” noting that the senator had connections with a member of the defunct Weather Underground, the radical antiwar leftist group of the 1960s and 1970s that planted bombs in the United States. Mr. Obama, who was a boy when the Weathermen were active, noted that he is also friendly with a very conservative member of the United States Senate, Tom Coburn, who once called for the execution of abortionists, and said he shouldn’t have to explain the views of every person he knows.

Mr. Finlayson, the trombonist, said his father, who fought in World War II and Korea, and was awarded a shelf of medals, flew the flag on the porch only on national holidays. “I suppose if Osama bin Laden showed up at Kennedy Airport wearing the Stars and Stripes on his turban, he just might get through,” Mr. Finlayson said.

Once, on an episode of “Seinfeld,” Cosmo Kramer got into a fight at an AIDS walk when someone tried to make him wear an AIDS ribbon, as noted by James Joyner on the blog, Outside the Beltway:

KRAMER (to organizer at desk): Uh, Cosmo Kramer?

ORGANIZER: Uh ...O.K., you’re checked in. Here’s your AIDS ribbon.