Celeste Wang, 20, from Belmont, Calif., said: “A lot of people use it as a proxy for saying they disagree with some of the ways you live your life. Even silly things like me carrying a water bottle around school has become a ha-ha.”

Preanka Narenthiren, a 19-year-old from Toronto, agreed. “I think that everyone from every other country feels some sort of moral superiority, especially about American politics,” she said. “As a Canadian, I’m guilty of this.”

Not everybody is deterred. Nikola Kralev, 20, said he was leaning toward accepting an offer to study at Columbia. “I mean, coming from Bulgaria,” he said, “I feel that America’s not that bad, when you consider history.”

But even among the realists, the American beacon has dimmed. Gergo Tóth-Göde, 19, a second-year student from Hungary, recalled being rejected by Princeton. Now, he said, it doesn’t seem like such a lost opportunity. For his third year abroad, he is applying to programs in China, Vietnam and Singapore, arguing that the future is in Asia.

Mr. Tóth-Göde said he was not troubled by the populist tactics of Mr. Trump. After all, he said, his own country just shook off a populist prime minister, Viktor Orban. “This is a hot take,” he said: Populism is “a phase.” The trouble is rather that the political upheaval in the United States has made it an unreliable place to study.