I took a look at SA back east, in a major american city where I live.
It was fun sifting through the postings seeking an older woman, of an ethnicity different from me, who I fantasized was seeking a man like me. My offering looked good on paper and I photograph well so I had good reason. I would check for replies frequently. I now think that that is all part of the game and the excitement that causes people to spend money in this way.
No one to whom I reached out—whose personal description I found attractive—replied. Those included people who listed exactly what I had in mind and were seeking what I thought I was offering. I received replies from other cities from other people I found unattractive—hyped, over eager, too beautiful and too young and I decided that they might even be false postings made by the SA staff to encourage hopefuls like me. Many seemed too good to be true, and others ridiculous.
There were dozens and dozens of postings so the odds appeared good, yet nothing came of it.
Mind you, I am patient and selective so I was not about to give someone a shot (or take a shot) out of desperation or to satisfy my loneliness, or horniness. I realized that if I did that, things might only be worse. I wanted someone who was curious, smart, and capable of understanding the process of having sexual encounters without paying money (for sex) or for the sheer fun of an illicit relationship.
Because of my experience, I do not recommend SA. In fact, I have tried a few other services and even went on one date with someone who was very nice, pretty, but who I deemed not suitable for me as I was at that time.
My guess? SA a way for an online business to collect email addresses of vulnerable men and women who might be open to offers that other people would not even consider. Or at least their collection is a side business that eventually brings in more than the main business.