Would it matter to you if Mona Lisa smiled more?

This sounds like a stupid question. Mona Lisa's enigmatic smile is inseparable from the painting. It's part of the reason tourists march to the Louvre every day and peer at the work through bulletproof glass. It's evidence of Leonardo's genius.

But what if it's not genius? What if it's dirt, bad restoration, overzealous cleaning, 500 years of wear and tear? What if Leonardo actually gave her a smile that was broader, warmer, less ambiguous? Would she still be great?

While you ponder those questions, let me ask some others. How would you feel if one of your favorite works, one you've seen repeatedly at a major museum, turns out to be a fake? Nobody knows how many phony works are on museum walls, but just about every major collector and museum has been fooled. Would you still value the aesthetic and emotional experience the phony work provoked in your mind? If not, does it mean that you were in love with the label - the artist's prestige and the value of the work as established in art-history books and at auction - and not with the art itself?

Tough questions, the kind that can drive a museumgoer crazy. I was inspired to ask them by two traveling shows currently at the Reading Public Museum: "The Secrets of Mona Lisa" and "Intent to Deceive: Fakes and Forgeries in the Art World." The Mona Lisa show is mostly about technology, while "Intent to Deceive" is about psychology, artistic technique, and, to a lesser extent, fraud detection. But both make us ask ourselves what we think we're looking at, and how we understand what we see.

"The Secrets of Mona Lisa" documents a high-definition photographic survey of the painting by the French engineer Pascal Cotte, and comprises images, most of them huge blowups using various infrared processes, as well as computer programs that attempt to correct for changes of the appearance of its pigments over time. The tone of the exhibition, with its purported revelation of secrets, is a bit promotional and basic-cable trashy. But still, if you really want to know what's in the painting, skip Paris and make your way to Reading.

Mona Lisa is so familiar that it is almost impossible to really see. You have probably never noticed that she doesn't have any eyebrows or eyelashes, have you? Cotte found one eyelash, and conjectures that she probably had more before a cleaning. The show also notes water damage in one part of the painting, which likely occurred when Napoleon kept it in his bathroom.

Cotte's photographs suggest the painting originally had a background of blue mountains and clouds, not the green ones we see now. The colors were livelier, and yes, she did have a subtly broader and warmer smile. We will never see this Mona Lisa, except in these photos, nor will we know whether this conjectured work approximates what Leonardo intended. If it does, would it have become the icon we know?

The most striking thing about the fakes and forgeries shown in "Intent to Deceive" is how phony they look. "Matisse would never have done that," you smugly say to yourself or your companion. That's because we know the works are fakes and are attuned to finding their shortcomings. If they were presented as authentic, we would concentrate on seeing their brilliance. In both cases, we see what we have been told to see.

According to one text panel in the show, "Experts estimate that approximately 40 percent of the art work circulating in the legitimate art market is inauthentic." That's vague sourcing and a shockingly high number, but it seems pretty obvious that we have all admired frauds.

The exhibition concentrates on five men who painted works pronounced by experts to be the real thing. Indeed, the faker has no career without credulous experts, and seeking their validation seems part of the lure of the crime. Han van Meegeren, the most famous of the forgers shown, created "Vermeers" that appeared to come from a period in the Dutch artist's life from which no paintings survive. He gave the connoisseurs just what they had been looking for, and for a time, his works seemed to document an "early religious style" for the artist that was widely accepted, even though there are no actual examples.

Eric Hebborn, another of the featured artists, is said never to have sold one of his fakes to an amateur, only to professionals who should have known better. He was inspired to make fakes, he said, after he was told by the eminent art historian Sir Anthony Blunt that he could draw like Nicolas Poussin. (Blunt himself turned out to be a phony of sorts, a key member of a Soviet spy ring.) As seems typical, Hebborn turned to fakery because his own works, and his old master-caliber technique, seemed destined not to sell in the modern-art world. But he did have a sociopathic streak. He first discovered his talent in the juvenile rehab center where he was sent, at age 8, after he burned down his school.

Elmyr de Hory claimed he could do Matisses better than Henri Matisse, though I can't help feeling that his Matisse-style Odalisque looks like a postwar American housewife. His pretense was that he was a European aristocrat who had come to the United States and was forced to sell off his collection. One of his first fakes, on display here, is a portrait of himself and his brother as children, enjoying a wholly fictitious privileged youth. It set the stage for the rest of his exploits.

Mark Landis never sold his work at all. He showed up at museums as a donor, sometimes in priestly garb, so he could bask in their gratitude. "Being treated so nicely by people was something I was unfamiliar with," he told an interviewer in 2013, "and I liked it very much." He seems to be a sad case, while John Myatt, the British forger, used his arrest and brief incarceration as a career stepping-stone. He now sells his variations of iconic works like Vermeer's Girl with a Pearl Earring for impressive sums, and he even starred in a BBC series in which he inserted celebrities into famous paintings.

"The shocking implication of the actions of these scandalous rogues is that their misattributed works have the ability to effectively sabotage the hierarchy of art and culture," writes curator Colette Loll on the exhibition's superb website, www.intenttodeceive.org. Many would call that a worthy aim for an artist's career.

Still, as even she notes, the keepers of that hierarchy - collectors and curators - are the ones least enthusiastic about expunging the phonies from their collections. They don't like losing their treasures, illusory as they may be. And, like the rest of us, they see what they want to see.



The Secrets of Mona Lisa and Intent to Deceive: Fakes and Forgeries in the Art World

Through Sept. 7 as the Reading Public Museum, 500 Museum Rd., Reading.

Hours: 11 a.m. to 5 p.m. daily.

Admission: Adults, $10; 65 and over, children, and college students, $6; 3 and under, free.