I don't, have in the past and it's ended ugly. I find that more and more of my time gets taken with messages and wanting my time socially. You can't become friends without letting slip personal stuff, and you really don't know of the guy is going to use it. Especially if you want to pull away, I keep escorting and clients separate. Of they want to go out for a coffee or dinner then it's still going to be transactional.
From those I have gotten friendly with, it ended badly. I have regulars that I've seen for years and they do ask to meet for coffee and I just tell them that I'm busy.