If anything, I think Rachel was inadvertently so. She tried being honest with Bruce, but he simply refused to see the truth in front of him. In TDKR, it seems that Selina is supposed to be the femme fatale, but that role is really Tatelia's. Yes, Selina is mysterious and sensual, and uses her feminine wiles to trick men, but she was always more or less honest with Bruce. Aside from locking him in with Bane, of course. (Although I'm not sure what else he expected, since she did do what he asked of her, no more and no less. Did he really think she would help him fight Bane? ) Tatelia seems on the outside to be pure of heart like Rachel was, but showed her true femme fatale-ness at the end. That trickery makes her the ultimate femme fatale, I suppose.