Once. He is one hell of a hottie and saw me three times inside of a week when I first went independent. After the third visit that week he asked me to dinner. I couldn't resist. We still see each other regularly. He buys me expensive presents (the latest was a pair of diamond earrings for Valentine's Day), is generous with his cash, and is a hell of a lay.
I can say that it won't happen again with another client though. I enjoy what I do but my FWB spot is filled. Of course now that I look back on the situation it seems more like a sd/sb thing.