It is a fine line between believable girl/girl lust and putting on a girl/girl show, and this mostly tends to go right down the line with an even distribution of both.
Sometimes it's quite good. Take Michelle B. and Jessie Summers or Jeanie Marie and Sonia. With nary a glance in the direction of the camera, they all keep their eyes on each other in a lustful manner and still manage to make one another the center of their girl/girl attention and actions.
However, a threesome with Malibu, Fallon Summers and Emilana starts out strong but ends with all three just masturbating with toys for the camera and neglecting each other.
Retailing: Girl/girl action in couples and threesomes. Toys.