Margaret Sullivan has written a beguiling memoir which shares many of the virtues of the work that brought her national attention as public editor of the New York Times and then as a media columnist for the Washington Post. The virtues of her columns, excellent news judgment and old-fashioned common sense, are again on display.

Especially in the early part of the book, Sullivan pats herself on the back quite a bit for breaking a glass ceiling by becoming one of the first woman editors of an important regional paper, the Buffalo News.

But she is capable of self-criticism, especially for a painful mistake when her paper decided to publish the criminal backgrounds of the victims of a mass shooting.

“The Black community was furious” because the paper had deepened “the pain of family and friends who were mourning their loved ones” – and “they were right”. Too often victims of police violence in Buffalo had been described as “no angel”.

She quotes Goethe on the benefits of such a mistake: “By seeking and blundering, we learn.”

The next phase of her career, when she identified the blunders of editors and reporters at the New York Times, then publicized them in her columns, is the most interesting part of the book.

Sullivan quickly learned what I discovered many years ago, when I switched from writing about politicians and prosecutors for the Times to critiquing journalists for Newsweek: reporters have by far the thinnest skins of any public figures. It’s not surprising: a big reason many choose to become journalists is to give themselves a feeling of being in control, so they often feel discombobulated when they are the subject of an interview instead of its progenitor.

To her credit, Sullivan offended the sports editor and the politics editor of the Times equally. She showed she had the right instincts with her first blogpost, calling for “rigorous adherence not just to the facts but to the truth, and away from the defensive performative neutrality that some were beginning to call false balance or false equivalence (‘Some say the earth is round; others insist it is flat’ or, more pertinently ‘Some say climate change is real and caused partly by human behavior; others insist it doesn’t exist’.)”

She almost never had “a completely comfortable day” as public editor, which means she did a good job: “If the people I worked next to were happy with me, I felt guilty for being too soft on the institution … If they were upset with me – sometimes even furious” she worried she had been too harsh.

One of her worthiest crusades was against the vast use of anonymous sources, especially in Washington stories. When Eric Schmitt, a national security reporter, was appointed to a committee on reporting practices, he was astonished to learn that readers’ “number one complaint, far and away, was anonymous sources”. A reader wrote to Sullivan: “I beseech the Times not to facilitate government acting like the Wizard of Oz – behind a curtain.”

Although Sullivan was at the paper a decade after its worst modern anonymous sources fiasco – dozens of stories promoting the idea that Iraq’s weapons of mass destruction were real – she found practically nobody had learned any lessons.

The practice was still “vastly overused … not just for ultra-sensitive reporting on the national security beat but also for all kinds of frivolous purposes – in gossipy entertainment pieces, in personality profiles, in real estate stories”. Sullivan inaugurated “AnonyWatch”, asking readers to send examples of anonymous sourcing.

Some of the very worst journalism practiced by the Times during Sullivan’s tenure was its coverage of the 2016 election. The paper’s first woman executive editor, Jill Abramson, assigned Amy Chozick to report on Hillary Clinton full-time in 2013. Another press critic, Tom Rosenstiel, pointed out it was probably a pretty bad idea to “perpetuate the permanent campaign” three years before the first primary.

Chozick’s first big feature for the Sunday magazine was called Planet Hillary, illustrated by an image of Clinton’s face as “a fleshy globe”. Sullivan agreed with the reader who wrote, “The now-viral image is hideously ugly, demeaning, sexist and completely premature.”

Times editors up to Abramson, who approved the image, “couldn’t understand the fuss”. To Sullivan it was an early warning that “when it came to covering Hillary Clinton, Times journalists often took things too far”.

Things went steeply downhill in 2015 when the Times – and the Washington Post and Fox News – promoted a book by the Breitbart contributor Peter Schweizer, Clinton Cash: the Untold Story of How and Why Foreign Governments and Businesses Helped Make Bill and Hillary Rich.

How Chozick chose to write about this crude propaganda? “Already the Republican Rand Paul has called its findings ‘big news’ that will ‘shock people’ and make voters ‘question’ the candidacy of Hillary Rodham Clinton”.

Things got dramatically worse with the paper’s obsession with Clinton’s emails, and FBI director James Comey’s decision to put them back in the news a few days before the election. By then Dean Baquet was Times editor. He vastly overplayed Comey’s announcement with three big stories, including one by Chozick and Patrick Healey headlined “With 11 Days to Go, Trump Says Revelation ‘Changes Everything’”.

Sullivan observes that framing must have caused “rejoicing in the GOP camp”. It did.

The Columbia Journalism Review reported that in six days, the Times “ran as many cover stories” about Clinton’s emails as they did about all policy issues combined in the 69 days leading up the election.

Comey shut down his investigation again. But the damage was done.

The Times editorial page compensated a little bit for its news coverage by giving Clinton an enthusiastic endorsement. But as Sullivan points out, editorials rarely sway elections while “relentless front-page political coverage can, especially when it’s in the hugely influential New York Times”.

“In this case,” she writes, “I believe it did.”

• Newsroom Confidential: Lessons (and Worries) from an Ink-Stained Life is published in the US by St Martin’s Press