Evangeline knows her body language. She can pick up hints and intentions from the slightest gestures, and therefore make her moves accordingly. It's part of her skill set as a thief, after all, and she's come to rely on it when it comes to both her assignments and regular life.
Although, this is surprisingly unhelpful when it comes to her luck with men. Despite knowing what they want, she can't actually tell when a guy really likes her. She's too used to the men in her life, the romantic part of her life specifically, having an ulterior motive when it came to dating. There's always something they've wanted from her, so she's come to expect it from people who show an interest in her. When she finds out that there is no other intention lurking behind their gestures, she's genuinely surprised.