I've had some encounters where both the provider and myself felt and were aware of some kind of genuine chemistry, whether it be purely sexual or a little more.  I've dated 3 providers to the extent that I could call them my GF.  One of which, though happening after she left the biz, was a serious relationship.  
On the flip side, I've had a handful of girls express interest in getting together 'off the books', only to have them not follow thru.  That's the part that annoys me, because while I understand it's an unusual way to meet someone and may make the other party feel awkward about the whole situation, I always give them an out and let them know they can tell me they've changed their mind and would prefer to keep it business.  They never take that option, so they lose a customer in the process.  It's all about being up front and honest.  
One girl told me she has a lot of her customers who ask to see her outside of business.  Her opinion is that eventually any guy would get jealous and have a problem dating a provider because the male ego would take over.