How reliable is Bob Woodward? From the very first there have been those who thought, well, he was making shit up. Lots of people questioned whether there ever really was a Deep Throat, for example, when All the President’s Men came out. Even after former FBI associate director Mark Felt claimed to have been Deep Throat, doubts continued that the former agent — his mind clearly fogged by age — was quite the drama-prone informer depicted in the book. Nixon White House counsel Leonard Garment noted one of the better known counterpoints in his book, In Search of Deep Throat — that Simon and Schuster editor Alice Mayhew, who edited All the President’s Men, “told [former presidential counsel John] Dean that she was the one who had invented the detective story structure for the reporters’ book. She also told Dean she did not believe there was a single source for Deep Throat.” Even Woodward’s iconic boss at the Washington Post, Ben Bradlee, told his biographer Jeff Himmelman, “You know I have a little problem with Deep Throat… There’s a residual fear in my soul that that isn’t quite straight.”

Woodward’s second book, The Bretheren, co-authored by Scott Armstrong, contained so many outlandish assertions about the behavior of Supreme Court Justices behind the scenes that, in a front page review for the New York Times Book Review, Renata Adler famously declared that every sentence in the book should end “with the caveat ‘if true.”‘

Then there was Veil: The Secret Wars of the C.I.A., 1981-1987, in which Woodward claimed to have gotten a sensational deathbed confession out of Ronald Reagan‘s CIA director William Casey. As John Cassidy detailed in a New Yorker story two weeks ago,

Casey, according to Woodward’s telling, admitted that he knew about the illegal diversion of monies from Iranian arms sales to the Nicaraguan Contras. “His head jerked up hard,” Woodward wrote. “He stared, and finally nodded yes.” “Why?” Woodward asked. Casey whispered, “I believed.” Did it happen like that? Even today, it’s a matter of dispute. In 2010, a former C.I.A. employee, who was part of Casey’s security detail, claimed Woodward “fabricated” the story after being turned away from Casey’s room at Georgetown University Hospital.

All of which was enough to make Joan Didion, in a memorable New York Review of Books essay, declare that “measurable cerebral activity is virtually absent” from Woodward’s books.

But perhaps never before has Woodward been subject to the kind of widespread and heated criticism he’s found himself subjected to over the last two weeks for calling an email from the head of the White House’s National Economic Council, Gene Sperling, a “threat.” See Cassidy’s New Yorker story for the full text of the email — and why most people are seeing Woodward’s thin-skinned interpretation of it as such a drastic mischaracterization that it’s led to the drastic reactions in turn. For example, see the Daily Beast column in which Michael Tomasky asks “Why does Bob Woodward get to lie — twice! — and still be Bob Woodward?” Or this week’s cover story in Newsweek by Max Holland, in which he observes that Woodward’s reaction to the Sperling email “reveals a grotesquely swollen ego fed by 40 years of hero worship.” Blunter still was the headline to Jonathan Chait‘s New York Magazine story last week: “What the hell happened to Bob Woodward?”

Interestingly, though, what may have been the most devastating attack to appear seems at first glance almost tangential: an article on Slate by Tanner Colby that isn’t even about one of Woodward’s political titles, but rather the one book he’s written that isn’t about politics: Wired: The Short Life and Fast Times of John Belushi.

As Colby backgrounds it,

When Wired came out, many of Belushi’s friends and family denounced it as biased and riddled with factual errors. “Exploitative, pulp trash,” in the words of Dan Aykroyd. Wired was so wrong, Belushi’s manager said, it made you think Nixon might be innocent. Woodward insisted the book was balanced and accurate. …Woodward being Woodward, he was given the benefit of the doubt. Belushi’s reputation never recovered.

But now, says Colby, he’s in a position to answer the questions that have once again arisen about Woodward in the wake of the Sperling-email furor — that is, “How accurate is his reporting? Does he deserve his legendary status?” As Colby explains, twenty years after Wired, Belushi’s widow Judy Belushi …

… hired me, then an aspiring comedy writer, to help her with a new biography of John, this one titled Belushi: A Biography. As her coauthor, I handled most of the legwork, including all of the interviews and most of the research. What started as a fun project turned out to be a rather fascinating and unique experiment. Over the course of a year, page by page, source by source, I re-reported and rewrote one of Bob Woodward’s books. As far as I know, it’s the only time that’s ever been done.

But what Colby uncovers isn’t a man making things up, exactly — not a liar, but someone more along the lines of Joan Didion’s knucklehead. As he explains in one long passage:

One of the things that was so spectacular to watch during the filming was the incredible connection that [Belushi] and [director John] Landis had. During the scene on the cafeteria line, Landis was talking to Belushi all the way through it, and Belushi was just taking it one step further. What started out as Landis saying, “Okay, now grab the sandwich,” became, in John’s hands, taking the sandwich, squeezing and bending it until it popped out of the cellophane, sucking it into his mouth, and then putting half the sandwich back. He would just go a little further each time.

In short, says Colby, he “spoke to almost all” of Woodward’s sources —

… some of the greatest writers, performers, and storytellers of the last quarter-century. … And if it were one or two people disputing Woodward’s characterizations, you might chalk it up to rose-tinted glasses. You might do the same if it were nine or 10 people. But when it’s practically everyone, when person after person sits down across from you and remembers, specifically … this is what Woodward mischaracterized and this is really what happened, a pretty clear pattern begins to emerge.

And whether that adds up to deliberate deception or simple tone-deaf reporting, it “helps explain the recent Sperling affair,” says Colby. “He took a comment from a source, missed or misinterpreted the subtext of what was being said, and went on to characterize it in a way that bore no resemblance to reality. What’s damning about the Sperling emails — and Wired — is that we can go back to the source and see the meaning and subtext for ourselves; normally with Woodward’s confidential reporting, we can’t.”

But it helps to explain more than the Sperling “affair.” Colby’s piece is one of the most in-depth considerations of the fact that Woodward’s faults are more complicated — and more troubling — than whether he’s a simple liar or not. As Colby observes, “when you imagine Woodward using the same approach to cover secret meetings about drone strikes and the budget sequester and other issues of vital national importance, well, you have to stop and shudder.”

Or, perhaps instead, you’ll be prompted to remember the passage in Woodward’s Plan of Attack in which he reported the thoughts of Colin Powell: “‘HOLY SHIT!’ Powell said to himself …”