He's right that we romanticize art theft and thieves. You know how handsome and ruthless those mastermind criminals are in the movies? Mr. Nairne pointed out several cases where a thief returned a valuable stolen painting- including the Mona Lisa, and no one believed that he was the thief because he didn't fit that romantic profile.
I know that thieves come in all shapes and sizes. I worked in a gift store for many years and we finally realized that most things were being stolen by nicely dressed middle-aged women. Many of my greeting cards were stolen over the years. I have to admit, it made me a little happy. Not only were people willing to pay for something I made, they were willing to STEAL it. I might feel a little differently if the cost of the stolen items was more than the $4.50 I sell my cards for though!