In the latest heist to shake the art world, three men wearing ski masks walked into the E. G. Bührle Collection in Zurich on Feb. 9, grabbed a Cézanne, a Degas, a van Gogh and a Monet together worth an estimated $163 million, and tossed them into a van and sped off. Though one thief brandished a gun, there were signs that the job was probably not up to robbery’s highest standards: the most expensive of the collection’s paintings were left behind (the four that were stolen were in one room) and the police said the stolen paintings appeared to be poking out of the back of the white van the men used to make their getaway.

Image A REFINED PALETTE Myles J. Connor Jr. has said he arranged the theft  and return  of Rembrandts Portrait of a Girl Wearing a Gold-Trimmed Cloak to avoid prison time in another art theft. Hes pictured in prison in 1997. Credit... J. Paul Getty Museum, left; Ed Quinn for The New York Times

“No one theory can fit all examples of art theft, but I think it’s often an I.Q. test for not-so-smart criminals, and a lot of them fail,” said James Mintz, the principal of a corporate investigations firm with offices in New York, London, Zurich and other cities that has handled art cases.

Many of the most notorious art thefts in past decades bear him out and illuminate a strange disconnect between the enduring mystique of art theft and the reality of its perpetrators. The theft in Vienna in 2003 of a gold-plated saltcellar made by Benvenuto Cellini, valued at $60 million, was traced to a 50-year-old alarm-systems specialist with no criminal record. The police, who caught him after he tried to ransom the sculpture, called him a “funny guy” who had decided to take the Cellini more or less spontaneously. A divorcé who lived alone, he kept the sculpture under his bed for two years.

Just last year, two men suspected in the theft of two paintings and a drawing by Picasso from the Paris home of Diana Widmaier-Picasso, a granddaughter of the artist, were caught on the street carrying the paintings, estimated to be worth more than $60 million, rolled up in cardboard tubes.

Law enforcement officials and officials with the Art Loss Register, a private database of lost and stolen art, emphasize that there are, certainly, highly effective art thieves at work around the world, in an enterprise that the Federal Bureau of Investigation estimates at about $6 billion a year in stolen goods. The marquee example remains the 1990 robbery of the Isabella Stewart Gardner Museum in Boston, the biggest art theft in American history, with a value estimated as high as $300 million. Speculation has run high for years that the crime, still unsolved and the art unrecovered, might have been carried out by the organization of James “Whitey” Bulger, the Boston crime boss, who remains a fugitive.