About 5 years ago, I answered an ad for a sex party off CL. I wasn't 100% sure what I was getting into, but I had to provide some photos before being approved and invited. It was $ 180 to get in. It was at a small apartment in downtown Manhattan. Six guys and four girls. One of the girls was part of a couple that paid to get in. The other three were paid by the host to be there. Everything was covered. Like Waterclone's experience, it was mostly M-F or M-M-F situations where the girl was sucking a guy off while getting fucked. Only two of the four girls interested me and one of them left early telling the host she was sick. So I spent most of the night trying to get a one on one session with the other girl that interested me, but I kept missing my opportunity. Long story short, I ended up sitting in the living room, talking to people for a couple of hours while drinking cheap beer and having no sex. It was a underwhelming experience. But, that was mostly on me, for being both disinterested and gun shy.
To make matters worse, the host lost his smart phone. It was a newer model phone at the time. At one point, he saw me looking at it. After I left, I got a text from another number, asking if I took his phone. I said no. I only had my own phone. The next day, he sent some vicious texts, flat out accusing me of taking his phone. I didn't take anyone's phone. But, between having no actual sex and being accused of taking a phone, I never tried to take part in another sex party/orgy.