The former Harry Potter star was invited to check out Hilton's mansion while making the new film, inspired by the real-life teens who snatched more than $3 million (£1.9 million) worth of goods from the Hollywood homes of A-listers.
Watson reveals she was in awe of Hilton's massive walk-in wardrobe, which was jam-packed with hundreds of pairs of designer shoes, as well as clothes the socialite had never even worn.
Watson tells the Radio Times, "It's almost like consumerism as a form of kleptomania. She could never wear all of those clothes and half of them were brand new and still had the price tag on. But I suppose she just bought them to have them. We've all bought things on impulse, but that's an entirely different thing."
The Brit insists her fashion tastes are much more modest, adding, "I've got about eight pairs of shoes and that's it."