In 2014, Newsweek revealed that Somaly Mam—the Cambodian anti-trafficking crusader endorsed by Nicholas Kristof, Sheryl Sandberg, and Susan Sarandon—lied about being sold into sexual slavery as a child, the story that underpins her wrenching memoir, The Road to Lost Innocence. When Mam was exposed as a fraud, the directors of the Somaly Mam Foundation forced her to resign from the charity she founded, and announced they would be “rebranding, renaming, and re-launching our organization.”

In 2012, Lance Armstrong’s unwavering insistence that he won seven Tours de France without using performance-enhancing drugs was shown to be a monstrous act of deceit. Armstrong was stripped of his victories, banned from bike racing for life, and compelled to leave the Lance Armstrong Foundation, which subsequently changed its name to the Livestrong Foundation.

Which brings us to Greg Mortenson, the exalted school builder whose bestselling memoir, Three Cups of Tea, is billed as “the astonishing, uplifting story of a real-life Indiana Jones and his remarkable humanitarian campaign in the Taliban’s backyard.” In 2011, Mortenson was unmasked on 60 Minutes as a self-aggrandizing fabulist who used his charity, the Central Asia Institute, as “his personal ATM,” according to the CAI treasurer. But unlike Mam and Armstrong, Mortenson wasn’t booted to the curb. Turning a blind eye to his dishonest words and deeds, the CAI board of directors continued to pitch Mortenson as the organization’s moral exemplar and guiding light, and kept paying him $169,000 per year, according to financial records released by CAI.

This is no small triumph for Mortenson, given the voluminous and irrefutable evidence of his misdemeanors. In 2012, Montana Attorney General Steve Bullock completed an investigation of Mortenson and his charity that resulted in Mortenson having to pay $1.2 million in restitution, including $214,000 he’d charged to CAI “for such things as L.L. Bean clothing, iTunes, luggage, luxurious accommodations, and even vacations.” Despite the ongoing scandal, however, the Mortenson cult of personality endures. He adroitly leveraged the allegiance of his most steadfast adherents to maintain control over CAI, which received about $3 million in donations last year.

Mortenson’s success at dodging accountability can be explained in part by the humble, shambling, Gandhi-like persona he’s manufactured for public consumption. But it also demonstrates how difficult it is to correct a false belief after people have made an emotional investment in that belief being true.

When our heroes turn out to be sleazebags, self-deception is easier than facing the facts.

Mortenson’s staying power raises doubts about the edict, generally accepted as gospel, that the best way to manage a public-relations crisis is to immediately accept responsibility for one’s transgressions and express remorse. Disregarding the conventional wisdom, Mortenson has maintained that although “mistakes were made,” he hasn’t committed any significant wrongdoing, which gives his supporters grounds for continuing to live in denial.

In Three Cups of Deceit, published in 2011, I detailed the whoppers that made Three Cups of Tea and its sequel, Stones into Schools, so captivating. His invented tales of derring-do turned Mortenson into a celebrity and generated $80 million in donations to CAI. But they also distorted the reality of life in the remote areas of Pakistan and Afghanistan where most of the CAI schools have been built, smeared the reputations of colleagues and villagers who assisted him, and promulgated ugly cultural clichés about the violent nature and religious fanaticism of the tribal communities he purported to help.

Mortenson has changed crucial details of his story several times in recent years, improvising on the fly with the instincts of a natural con artist, boldly layering lie upon lie to confound his inquisitors. One might think this periodic rescripting would eventually catch up to him, but the tactic appears have worked pretty well thus far. Oversight of the nonprofit sector is lax. It’s not hard to game the system. And when hagiographic fables about Potemkin heroes like Mortenson and Somaly Mam become lodged in the popular imagination, they acquire a sheen of legitimacy that makes them tough to debunk.