"What I really like to do is look at the books that are out for people to see -- 'Look at my highbrow interesting things' -- and compare them to ones in the private places," he said.
"I'm quite conscious about thinking when am I in the place that is for others to see, when am I in the private space ... and that can even be within a room," he said. "So when I go to an office, for example, I look at the things that are facing you as a visitor and then crawl underneath the desk, behind and see if that's where the stuff is being hidden."
And if you've been snooping in your neighbor's medicine cabinet, you might be surprised to learn that isn't the best place to start.
"Medicine cabinets are surprisingly uninformative because there's such a standard vocabulary of items within that," he said. "Same thing goes for the refrigerator. That's often thought to be very revealing, but they don't vary that much."
And you shouldn't feel guilty about snooping, because you're not the only one.
"I think nearly everybody snoops to some extent," he said.