Only once and it was total turn off.
About 10 years ago I arranged a punt with a SP I had not see before. I had seen pictures of the SP but not their whole face. When I entered her flat and she step out from behind the door, I realised she looked like a woman I worked with.
Once I got over the surprise, I thought it would be fun to fuck the lookalike as I didn't like the woman I worked with and the thought of role-playing I was at work stuffing my cock in her mouth to shut her up was a turn on.
As punt went on I discovered not only did the SP look like the womam I worked with she also acted like her and talked constantly about herself and how everyone thought she was great.
After 10 minutes, I had lost all interest, she did try to get me going but it wasn't to be. That the only time I haven't manage to cum during punt.