NEW YORK -- Wayne Barrett had considered his 1992 book on Donald Trump to be a commercial flop. Though Trump was “king of the hill” when Barrett signed the publishing contract, he was “a joke” by the time the book actually came out, Barrett remembers. The press and public had soured on the high-flying mogul awash in debt.

But Barrett’s trenchant and out-of-print biography, Trump: The Deals and the Downfall, is a hot commodity these days, selling for hundreds of dollars on Amazon. His Brooklyn basement, littered with boxes of files on Trump, has also become a destination for investigative journalists digging into the Republican front-runner’s spotty business record. Barrett, who began covering Trump in the 1970s for The Village Voice, has revealed the real estate developer’s ties to mob-controlled businesses and other unscrupulous characters. If he weren't currently dealing with health issues, he said, “there would be a hundred different ways I could look at this book and advance it.”

Some veteran New York City journalists, such as The Smoking Gun's William Bastone, The Daily Beast's Michael Daly and The New York Times' Charlie Bagli, have recently explored Trump’s business dealings and associations in the context of the current presidential campaign, Barrett said. But he argues that the broadcast media has “totally failed” in its obligation to vet the candidate. This election cycle, Barrett said, he's been approached by dozens of journalists, including some hailing from TV networks in Canada, Germany and the United Kingdom. So far, only one U.S. network journalist has called.

Trump has dominated the national media over the past nine months, especially on television, where his ratings lead to big profits. In countless interviews, debates and televised rallies, Trump has touted his business record in arguing that the United States needs a brash deal-maker instead of another do-nothing politician. In a Time cover story published Thursday, Trump said he's "built an incredible business" and described himself as "the most successful person ever to run for President."

Bebeto Matthews/ASSOCIATED PRESS Trump University is now the target of fraud lawsuits.

Yet Trump’s business dealings -- complete with multiple casino bankruptcies, failed branding ventures, employment of undocumented immigrants, long-reported ties to mob-run businesses and the promotion of a real estate training program that's now the target of a $40 million fraud suit -- has received less sustained coverage this election cycle than his countless Twitter spats, outrageous remarks and rank bigotry. While Trump promised last summer to disclose his tax returns, he continues to stall, thereby preventing journalists from assessing his grand claims about his personal wealth, charitable giving and "Apprentice" salary.

“I think there’s ample room for the media to scrutinize his business record much more closely,” said Timothy O’Brien, author of the 2005 book TrumpNation: The Art of Being the Donald. In that book, O’Brien reported that Trump’s wealth was closer to $150-$250 million than his stated $10 billion. Such revelations prompted Trump to sue, unsuccessfully, for $5 billion.

O’Brien, a former editor at The New York Times and The Huffington Post who served as Barrett’s research assistant for his Trump book, now writes on Trump for Bloomberg View, where he is executive editor.

In late January, O'Brien looked at how Trump has made his record as a deal-maker “the litmus test of his candidacy,” even though “a well-documented and widely reported trail of bad deals litters Trump’s career as a real estate developer and gambling mogul.” He zeroed in on Trump’s failed real estate project on Manhattan’s West Side, a botched deal that “should be of interest to anyone looking for insight into how Trump might perform as president.”

Similarly, The New York Times' David Segal revisited Trump’s 1988 purchase, and loss, of Manhattan's Plaza Hotel in a January story. "The more you know about Mr. Trump’s past, the more his run for high office looks like an effort to close the biggest deal of his life,” Segal wrote.

Over the past couple weeks, the Times has also reported on Trump’s tendency to hire foreign workers for his Mar-a-Lago Club in Palm Beach, Florida, and how his influence in New York real estate has waned over the years as he's turned his focus away from development in Manhattan and more toward international branding opportunities.

Michael Bezjian/Getty Images Several ventures over the years, including Trump Vodka, Trump Steaks and Trump Mortgage, have been shuttered.

There have been other good instances of digging into Trump's past, even if such accountability reporting has usually been dwarfed by coverage of the latest offensive remark coming out of Trump's mouth.

The Washington Post’s Robert O’Harrow Jr. reported in October that Trump made large campaign contributions to politicians tied to his early projects, and that he worked with mob-controlled companies to build them. In revisiting this era of Trump’s life, O’Harrow acknowledged that Trump's early days have been covered in the past, but noted that “many details have been obscured by the passage of time and overshadowed by Trump’s success and celebrity.”

BuzzFeed, which has scrutinized Trump’s record and past claims more than most outlets this cycle, seized Wednesday on a 2005 blog post in which Trump expressed support for outsourcing -- a position that runs counter to his campaign pledges to protect American jobs.

But the broader media trend during the early months of Trump's campaign was to treat him "as a carnival act," according to O'Brien -- which likely resulted in less rigorous coverage than there might have been. (HuffPost put its own coverage of Trump in the Entertainment section instead of Politics for several months, although its reporting on Trump was essentially the same as on other candidates.)

“I think the GOP thought about him in the same way," O'Brien said. "He’s not going to go away. I imagine you’ll see the media now taking a closer look at him in greater depth than they have in the past year.”

Coverage of Trump's past does indeed seem to be on the rise, and not only from traditional media players.

On Sunday, HBO’s John Oliver spent better than 20 minutes puncturing the myth of Trump as a master deal-maker and mocking a slew of failed ventures bearing the mogul's name, such as Trump Vodka, Trump Steaks and Trump Mortgage. In a segment both seriously researched and seriously funny, Oliver dubbed the candidate a “litigious, serial liar with a string of broken business ventures," as well as "a bullshit artist."

Trump's business career is sure to get more media attention now as anti-Trump forces, including former Republican presidential nominee Mitt Romney and a newly formed super PAC, mount a last-ditch campaign to portray the front-runner as a fraud who's taken advantage of Americans through schemes like Trump University. Trump's primary campaign rivals failed last year to attack Trump's record, a mistake the Democrats promise they won't make if Trump wins his party's nomination.

Of course, journalists didn't have to wait for political campaigns to leak opposition research, given that Trump's questionable record has been hiding in plain sight.

Pulitzer Prize-winning journalist David Cay Johnston got to know Trump during his time as Atlantic City bureau chief for The Philadelphia Inquirer, from 1988 to 1991. He wrote about the mogul in his 1992 book Temples of Chance: How America Inc. Bought Out Murder Inc. To Win Control of the Casino Business.

Back in July, as TV networks began obsessing over the font of controversy (and ratings) that was and is Trump, Johnston posed 21 questions for the candidate in an open letter for The National Memo. Among other things, Johnston asked about Trump’s claim of being an “ardent philanthropist,” his having bought concrete supplied by two crime families, his employment of Polish construction workers who were in the country illegally, and his involvement with the now-defunct Trump University.

Johnston told HuffPost he wrote the “21 Questions” piece to prompt journalists to dig into these matters, which are “all in the public record.” He's since written several more pieces about the front-runner, on topics ranging from Trump's tax returns to the time Trump helped suppress an unfavorable documentary 25 years ago. (The film is now available online.)

Johnston is especially surprised that more reporters haven't written about how in 1987, Trump sought leniency for Joseph Weichselbaum, a convicted cocaine trafficker whose company supplied Trump with helicopter services. Both Bastone and Daly have recently reported on the Weichselbaum connection, but there's been scant coverage elsewhere -- even as Trump has labeled Mexican immigrants “drug dealers” and promised to build a "big, beautiful, powerful wall" on the U.S.-Mexican border.

“If Donald Trump were to become president, he is the first person I know of who would be in the White House in modern times with deep, continuing associations with mobsters, con artists, drug traffickers, convicted felons -- gratuitously involved with these folks,” Johnston said. “That deserves enormous inquiry.”

Editor's note: Donald Trump is a serial liar, rampant xenophobe, racist, misogynist, birther and bully who has repeatedly pledged to ban all Muslims -- 1.6 billion members of an entire religion -- from entering the U.S.