"No matter how I answer that I will be in trouble," she said when asked who was the better kisser. "Both were pretty beautiful partners."
In an interview for the November 2009 issue of Vanity Fair, the brunette bombshell dished on her kissing scene with Theron in the 2004 film "Head in the Clouds" and her smooch sesh with ScarJo in "Vicky Cristina Barcelona" and talked about her fascination with women.
"It was my first acting school. I would pretend to be doing my homework, but I was really observing the women," she confessed in the candid interview.
"I found their behavior mesmerizing -- what they were hiding how they left feeling a littler different after they'd been helped to become a little more like whom they wanted to look like. They treated the place a bit like a psychologist's office," she told the magazine.
"They would share all their secrets."
The actress has two new films -- "Broken Embraces" and "Nine" -- and said her love of acting began at an early age when she found little solace in schoolwork.
"I really didn't want to have to be in an office," she said. "I was a good student, but not happy. I thought, I have nobody in my family and no friends who can make a living out of anything related to an artistic profession, but I want to try."