Interaction off the dancefloor is what matters. Does she linger after you dance or does she make a quick but polite get away? Does she ask about your life away from dancing? Is she REALLY interested in your stamp collection, the fact that you play the oboe, or can do a great impression of Robert DeNiro? Does she mention wanting to see you away from your salsa club? Is she constantly watching you only to turn away quickly when you catch her? Or does she stare into your eyes just a little too long? Stand just a little close? Laugh at your jokes just a little too much? Brush her hand against your face? Brush her arm across your body? Has she ever blushed when you looked at her? That's how you tell. How well she follows on the dancefloor has nothing to do with it.