Whether that “no” is verbal, physical, or simply one’s attitude, if someone seems disinterested, leave them alone. This should go without saying, but no means no. Some may have separate areas for cruising and areas for relaxing and talking. Some are not places where loud, protracted conversation is inappropriate. Similarly, sex parties - both public and private - vary in vibe. Don’t ruin a great party for everyone else. Disregarding them may get you permanently banned, and could threaten the safety and viability of the event itself. Commercial venues often have rules prohibiting drug use, prostitution, and other illegal activities. Many private sex parties will ask that you enter quietly - especially if the party is located in someone’s apartment - and not loiter on the premises after you leave.
Follow the rules and respect the atmosphere.