People have a fascination with forgery. Perhaps it’s because the art world has been so overinflated that when we hear about the Leonardo da Vinci selling to a Saudi prince for $450 million and then have it turn out to be most likely fake, we respond with glee. There’s something of a Robin Hood complex about it all: Only the ultra-rich are being swindled, so what’s really the harm?

“It’s absolutely not da Vinci,” says Robert Driessen of that spectacular auction. A former art forger, he says he can spot fakes a mile away. “Have you seen the before restoration and after restoration? It’s a totally different painting now. It’s unbelievable how people can fall for that.”

By his own estimate, Driessen created thousands of forgeries during his run as a forger in Europe, starting with oil paintings, then moving to sculpture. He sold these works to collectors, who, knowing they were fake, would then take the pieces to auction. At the apex of his forging career, he focused his production on Giacometti sculptures, before his arrest in July 2014. He spent a few years in prison, then relocated to Thailand, where he still makes Giacometti reproductions—with the disclaimer that they are not originals.

Driessen called me from Thailand to discuss his life’s work and perspective on forging. From our interview and from his self-published memoir, it’s clear that Driessen intended to be an artist himself, but fell into forging when he desperately needed money and received a commission to paint 19th century Romantic-style Dutch and German landscapes that weren’t exactly meant to be forgeries, per se, but also weren’t exactly meant to be anything else.

He wavers between remorse for his wrongdoing and denouncing the art world as essentially being no better, therefore justifying his work. “I really mean it from the bottom of my heart: I love art, I dream art, I eat art,” he says. “But the art world is so loathsome you wouldn’t believe.”

There’s an obvious incentive for auction houses to inflate the value of a work, which can be done in a variety of ways, from accepting something widely believed to be fake (see: Salvador Mundi), to price fixing (see: Christie’s and Sotheby’s ). The house always wins, and even the littlest white lies can begin to stack up.

“They take a glance at where it comes from, and as long as they can sell it, they need art to sell,” he says. “As long as it looks good and they’ve got some reference, they don’t really care where it’s from.”

“I think that 30-40% of all the auction houses is forged art,” he adds.

The normal process for selling work from a private collection at auction involves having the work authenticated by a third party expert; the collector then takes their work and the authentication certificate to an auction house, like Christie’s or Sotheby’s, who then sets a starting price and brings it to auction. Intentionally or not, there’s a lot of room for error in the authentication process.

Not every work by an artist has been documented, and artists often change styles throughout their career. There is rarely one singular marker that will clearly separate the fakes from the originals. It’s almost impossible to be certain, so, claims Driessen, most authenticators give objects the benefit of the doubt.

Would a database like Artnome’s compiling the top 40 artists’ known works help combat incorrectly authenticated forgeries? “Yeah, but I don’t think it’s possible,” he says. “Artists, if you’re talking about the top 40, you’re talking about Picasso, Giacometti, Cezanne. These people hardly ever held records, and you still find in attics or basements some piece which is not registered. Of course most of them are fakes, but sometimes a good piece turns up. The problem also is, if it is an original piece and you go to an expert, the expert will not want to burn his hand and say, ‘No, I don’t think it’s original.’ That also happens.”

But, authenticators can be persuaded to give something the benefit of the doubt: “If a piece is good, if a piece is almost original, I do know from experience that if you say to an expert, ‘If you say it’s original, and I put it in the auction, and for the selling price, I’ll give you 20%, 30%, 40%’ — if it’s a piece that brings $10 million, come on! It’s a million [dollars] just for the expert to say ‘yes’.”

There’s also a built-in protection for the expert, should things go awry and the piece is discovered to be a fake: “They say, ‘Well, I can’t know everything. To the best of my ability, I thought it was genuine.’ That also happens.”

The line between real and fake, authentic and inauthentic, can also be tenuous when looking at sculptures that are made from casts. Take Rodin, who willed his estate to the Nation of France in 1916, which authorized the government to make posthumous casts. There are some provisions; the date of the cast has to be inscribed on each sculpture, to delineate between those that were made by Rodin’s hand (or, if not by his hand precisely, at least made during his lifetime) and those that are being cast posthumously.

Every cast that the government makes of Rodin’s sculptures is, technically, a Rodin sculpture. What, then, separates that from the works by Driessen or other forgers who used casts they took from the original sources — are they any less authentic than a government-cast Rodin?

In his memoir, Driessen talks about the prevalence of family members creating posthumous casts to make more money after an artist’s death, citing the German sculpture Wilhelm Lehmbruck as one example, with his widow casting many more pieces from his original molds. “I made Lehmbruck, as well,” he says, “but his wife did the aftercasts, and she wouldn’t let anybody be involved because she wanted all the money. Everything that she knew wasn’t made by her, she called fake.”

“It is of course an extension of the original,” he adds. “But people don’t call it that way. They say no, there’s only five works, and now suddenly there’s 15 or 150; it’s still the same thing, but you can’t call it original anymore. But it’s still the same sculpture.”

I mention how this inflation ultimately lessens the value, which affects both the artists and their families and all of their patrons; I ask if he’s ever had ethical qualms about his practice as a forger and how it can affect others in this way. “Not whatsoever, actually. I never went to an auction house myself,” he says. “I sold it to people who were interested, and they knew what I was doing, but I never made the big money. I sold it for little money, and that’s how I lived my life. I was just making art.”

He catches himself. “Not making art. I was copying art. I’m not an artist.”