Liu Mingjie learned the latter lesson. He is the designer and entrepreneur behind the popular “Oba Mao” image, which takes a silk-screen likeness of Obama and dresses him in a green jacket and cap to resemble the late Communist leader Mao Zedong.

Since September, Liu’s shop had been doing a brisk business selling the hugely popular Oba Mao T-shirts, purses and magnets. Oba Mao became one of the hottest-selling items in town, particularly among urban young people and online “netizens.” Oba Mao melded two iconic images — even if no one could explain precisely what it meant.

But suddenly last week, Liu had no more supplies, and no explanation why.

Liu nervously did not want to answer a reporter’s questions. He also removed most of the Oba Mao articles and photos from his blog.

But neighbors in nearby shops reported that they were all visited last week by uniformed officers from Beijing’s Industry and Commerce Administration and were told they were not allowed to sell anything with Obama’s image, and particularly not Oba Mao items.

“My understanding is it is related with Obama’s China visit,” said one sales clerk from a shop selling matchbooks with colorful covers. “They think that stuff with Obama’s image might be insulting.”

Yao Lan, the sales manager for another souvenir shop selling T-shirts and toys, said: “Yes, it is true, we have been told not to sell any Obama-themed stuff. The government officials visited our store and told us not to do that.”

“My understanding is, as Obama is visiting China, our government is making a good gesture not to embarrass him with that stuff,” Yao said. “I think the U.S. government would do the same thing if Chinese leaders are visiting the U.S.”

But another Beijing shop, called Grifted, selling politically themed merchandise, seems to have been immune from last week’s crackdown. The store was selling an Obama action doll dressed as Superman, right next to Mao in uniform.

P.P. Xiong, the creator of the Obama-Superman toy, said he came up with the design because “I like Obama a lot. And I made such a design after the inauguration. I think American people have high expectations for Obama, and I hope he will come to help the U.S. just like Superman.”

For the record, at least two officials of the Industry and Commerce Administration denied the shopkeepers’ claims that they had been asked to stop selling Obama merchandise.