Are there stories about sex worlds where promiscuity is the norm, there are little to no taboos, and open, casual and public sex and orgies is part of their way of life?
Gorn, Riza (Star Trek), there's one I can't remember right now about a world where dragons produce a liquid that is both a powerful drug and aphrodisiac and everyone is fighting over it when they aren't screwing like crazy
On here? I haven't checked too deeply but usually it's alien worlds and even then sex isn't that world's focus, just the story's. I remember there was a comedy series called Porno Land which I think had that concept but I didn't read it at the time.
This thread got my attention because "Sex World" is the title of a classic (1978) porn flick that's on a lot of "Best Porn Ever" lists. Annette Haven, Kay Parker (in her first on-screen sex role), John Leslie, Joey Silvera and others.
The movie is named for a resort where counselors discover your greatest sexual fantasy and the staff then fulfills it. It was a life-changing experience for some of the characters.
We can presume SF-wise that every civilized society has taboos embedded in it, including sexual proscriptions. The nature of such taboos will vary between cultures. The fun comes when culture-surfing various civilizations, finding what's fuckable and what's prohibited. Pick the pleasure planet of your perversion.