I'd be a prosecutor's dream- nothing would remotely phase me. Living in Los Angeles in close proximity to adult film studios can desensitize you to everything.
I listened to that tape waiting for some big :what: moment to happen, and I just didn't hear it. It sounded like a tired guy and a chick trying way too hard to keep him sexually engaged. She was willing to do anything, including employ baby talk, which she carried into her fauxgasm. He just reacted to her "performance." She lead, he followed.
Roleplay, pure and simple. Nothing sinister about it at all, save her taping the call without his knowledge. Indicative of deviance? Puh-lease. I am hoping the jurors are like-minded.