The effect of these caustic campaigns is a darkened view of the president, personally, but also of the presidency itself. The institution is weakened if partisan attacks on the chief executive's patriotism become status quo.
And so, curious about the source and depth of Giuliani's sentiments, I stood at the voting station and asked more than two dozen CPAC conservatives whether Obama loves his country.
A dozen said yes.
A dozen said no.
Six others said they weren't sure but leaned "no."
The "yes" voters tended to be younger. They answered quickly and clearly. "I'm sure he does, sir," said William Winston, a 20-year-old military student at the Citadel. "But he just loves it the wrong way."
"I don't think you can put in the work and effort of becoming and being president without loving it," said Anthony Rubino, a 20-year-old University of Maryland student. While Rubino believes Obama is a bad president, he says, "It's ridiculous to say he doesn't love his country."
The "no" voters tended to be older and answered tentatively. Their justifications were almost uniformly rooted in Obama's policies or his past statements—quotes with little context. Their articulation echoed conservative media commentators.
"No, he doesn't love or like America," said Chris Phillips, 58, of Sterling, Va.
I asked why.
"Actions he took," the retired federal worker replied. "As a community organizer, he had a major disgust with the country as it was currently constructed."
Based on what?
"The people he associates with, like Reverend Wright."
I joked that we all should hope we're not judged based on the worst one or two people in our lives.
Phillips pressed me with a conservative meme: "He said he wanted to fundamentally transform the country."
I reminded Phillips that Abraham Lincoln fundamentally transformed the country, and just a few hours before our conversation, Republican Gov. Scott Walker of Wisconsin drew applause at CPAC for promising to "transform America."
Phillips shook his head. "I missed Walker's speech," he said. "But the country will need to be fundamentally transformed after Obama."
He chuckled at his own circular reasoning and backed off a bit. "Obama has a great dislike for the country he grew up in and a country he leads."
Also evolving during our conversation was Ben Idzik, 18, of suburban Detroit, whose first words were, "He doesn't love America or its traditions." We chatted about his reasoning before shaking hands over a final question.
"Do you think I love my country?" I asked.
"I don't know you, but I take your word for it," Idzik said. "I can't read somebody's mind and say they don't love their country."
Can you give Obama the same benefit of the doubt?
"Yes," he said.
None of us reads minds. None of us knows what's in other people's hearts. But we do have opinions and the right to disagree with our presidents. Fight them, politically, when their policies and values run counter to ours. Why can't we just leave it at that?