I have a regular who has been trying to get me to go for lunch after our meets in the morning or to join him out for the day on his boat and up until now I have always declined. This is partly due to finding the whole idea mentally exhausting and as nice as he is, he wouldn't be someone I would choose to spend time with socially. I also always suspected that he wouldn't see it as additional time to our usual private time together and therefore have no intention of paying a fee for my time.
So the other day I called his bluff and said yeah let's go out to a country pub, It's X amount for an hours social time. He looked absolutely shocked and said he thought we had become friends after all these years and what he gives me anyway he sees as just a 'donation'! So shows the total disconnect there can be! I'm glad now I've always kept it to good old simple and structured private time, otherwise with this guy the boundaries would've have become easily blurred.
I think it depends on the person though and some clients 'get it'. I find social time works better with someone who is just passing through area and is not going to be a regular. They just want a drink etc whilst they are staying at their hotel for example. I