When a group of transgender women are out on the town, the ability to pass as a female drops precipitously as the number of girls increases, or the pass-ability of the girls decrease. The very passable, young TG women are given a 0, and with age, features, voice, etc, that number can increase to 10. As the group score approaches 10, the group, as a whole, runs the risk of collectively being "outed."
Let's see, she is a 1, she is a 2, she is a 0, she is a 1, but her....shes a 7 so we might not want to invite her. She'll throw off the tranny math.