What makes the argument so strong is the verbal volley. At one point, the director asks if she’s "done this before." Instead of a porny "I love it," Ivy whispers, "Not… not for a job, no." This line single-handedly sells the entire premise. She then asks, "Will this actually get me the part?" The director’s grunted "It might" is a masterful piece of improvisation. It’s ambiguous, coercive without being threatening, and utterly believable.
The best proof of authenticity is the aftermath. Most scenes cut abruptly. Ivy’s scene includes a full 90 seconds of post-coital silence. She lies on the dusty couch, staring at the ceiling. The director asks, "You okay?" She laughs—a real, shaky, relieved laugh—and says, "I think so. Do I get the job?" The director says, "We’ll call you." She is left sitting there, alone, pulling her tights back on. It is devastatingly real.