Mr. McClellan’s book chronicles how Mr. Bush staked that credibility on the false rationale for the Iraq invasion — that Saddam Hussein had weapons of mass destruction — and ultimately lost the confidence of Americans, hobbling him for the rest of his presidency.

But the damage wasn’t isolated to Mr. Bush’s political standing. To this day, the American intelligence community must contend with lingering questions about its own credibility — to wit, taunts from Moscow (not to mention from Mr. Trump) that assessments pointing to Russian meddling in the presidential election are questionable. After all, wasn’t it wrong about Iraq?

There’s a big difference in importance between the size of Mr. Trump’s inaugural audience and the intelligence that led to war, no question. And, as the former Bush White House press secretary Ari Fleischer noted in a conversation with me on Sunday, it’s way too early to say whether Mr. Spicer’s weekend performance will be the norm.

The Trump team’s emotions were raw over the weekend, Mr. Fleischer noted, after a mistaken pool report was sent to the rest of the White House press corps, claiming that Mr. Trump had removed a bust of the Rev. Dr. Martin Luther King Jr. from the Oval Office. Zeke Miller, the Time magazine journalist who had written the report, quickly corrected it and apologized when the White House alerted him to the error.

“It rightly leaves the people inside feeling that ‘reporters were opposed to us all along for being racist and the first thing they did was imply we were,’” Mr. Fleischer said.

Still, the weekend’s events did not arrive in a vacuum. There was the report last week in The Washington Post that the Smithsonian’s National Museum of American History, known for high standards of accuracy, was selling a commemorative book about Mr. Trump riddled with questionable notions, such as that Hillary Clinton deserved more blame than Mr. Trump did for the so-called birther campaign questioning Mr. Obama’s citizenship. (After that report, the museum said it was removing the book pending an investigation into whether it met standards for accuracy.)

The administration’s decision to eradicate nearly any reference to “climate change” on the White House website could be expected given Mr. Trump’s promises to overturn his predecessors’ climate policies. But it set off concerns among climate scientists that it would extend to valuable government data — fears that also apply to the sanctity of other administration-controlled data. (Mr. Fleischer, for one, noted that career bureaucrats would blow the whistle on any moves to manipulate government data.)