And to a minor extent, that’s true of “Art Detectives” on Acorn TV, about a policeman who heads up the one-man Heritage Crime Unit in the U.K. His specialty is crime linked to the art world.

Police cars are driven hard, but that's not the only reason you might not want to buy a used one at auction. In a surprisingly not uncommon scenario, man buys old police SUV, but has to call the ...