No North with respect to her demeanor, there is a certain alter ego that encompasses her persona for purposes of economic necessity which is on display during the course of your interaction. With that said, this is when all of the other elements of that persona are available to you to get you relaxed and to satisfy you because it is all about you for that time period. The question is after you get to know some of them and I am sure that you do, do you get to talk about them and see what there concerns are and how they feel about life and other interest sans the copulatory.  Those who do obviously are comfortable with you and have interest with you that are outside the parameters of the standard provider\client relationship.  

However there are a few or most of your encounters that just want to get you erect and collect while being mechanical and professional about their duties while bequeathing the booty. Those situations tend to be ethereal and ephemeral in nature and I am sure those are the ones that you tend to distance yourself from as time goes on. I think you see this with respect to the development of your encounters as you try to look for those which tend to be deeper in a variety of other areas.