My users know that Conversations aren't private from me IF needed...they do know I can go into the database to read if the law required me to do so.
But like me, they expect their conversations to be among themselves. Yes, I edited my Terms and Rules but left the ones XF puts in there at the bottom to cover myself.
I have a forum where we have a 2 individuals help others fight insurance companies. Initial contact is made on the forum, further contact is switched to conversations and from there, it goes to email, then phone calls. Since I already know the email of both members helping, AND I encourage people needing their help to get their help, why should I read the conversations.
My users are quick to report spammers and even screen shot if needed.