I've been to Fetish Affairs parties probably 12-15 times.
The good: Lots of women to choose from, most of the girls are American, and the girls (and guys) are a lot more normal than at least I expected. (I was kind of fearing a super, creepy dungeon vibe with a bunch of non-verbal types, staring at you weirdly.) But the main advantage is the selection of women is large enough you have an excellent chance of finding someone fun.
The bad: Super crowded tiny spaces, bumping into people all night, and the session areas are so small that the flimsy curtains are half open half the time providing hardly any privacy. And his so-called "room" isn't really a room at all. Also, plenty of unattractive women who come up and talk to you, and you have to find ways to politely send them away. But they want money, so the unattractive ones sometimes cling to you like barnacles.
Alternative event:
https://www.footfetishnyc.com/home
This party actually does have rooms with doors (they're old private karaoke rooms). While it's billed as a foot party, I've ticked lots of girls there all over.
The downside to it, a lot fewer girls -- only about a quarter of the number of girls at the Fetish Affairs party. Also most of the FootFetishNYC girls are foreign -- sometimes never even that great at speaking English. But at least if you do get lucky here with finding the right girl at FootFetishNYC, you can get a legit private room.
Bottom line -- you should try both.