Dated a chick who contracted so hard her tenderbits would suck in air and queef it out. Sounded like a sick bulldog. The she would giggle uncontrollably. First time was a lot to take in all at once.
I'm a foot watcher, if the toes are doing shit that can't be consciously duplicated, you nailed it.
Also the ugly factor. If a girl is faking, she doesn't want to look bad... If its real she will get her "ate too much chipotle" face going. Aka vinegar strokes