Spy mode
Definition
Spy mode (sometimes “spy show”) lets you watch an ongoing private show without the performer getting a name-drop that you joined. You still pay. You usually cannot chat.
Why it exists
It is extra revenue on a session that is already happening. Some performers turn it off or charge more for exclusive so it cannot happen. Some leave it on because it pays.
If you are the paying private
Ask, or look at the room settings, before you assume you are alone. If the idea bothers you, use exclusive or a site that does not sell spy access.