I have never experienced it.  I did have a buddy earlier this summer tell me about an encounter he had.  It was at a DIY place, and not only did it go to unplanned FS, it was BBFS.  Not very smart, or safe.

If you want FS, pony up and see a FS provider.  Chasing something that can be unattainable would likely cost more, and be more frustrating.

The ladies, although business personnel are also human beings first.  If you are an individual that ladies in society generally would be interested in, then guess what there's always a chance.   I was just having this discussion with a friend and provider just last week.  If you treat the ladies with respect, are interesting, clean and well groomed, it might happen.   If you cant recall the last time a shower was utilized, then DIY might be a better expectation than YMMV.

I have a massage provider that I have seen for a long time. We clicked and now almost every time we together is ends in FS. The best part is because we click and we both always have a really good time. It is off the clock and no extra charge. Before everyone starts PMing me and asking who it is. She is UTR and I will NEVER tell so please don't ask. But yes it does happen. PS it is always 100% safe.