Do admins read pms?

Can anyone tell me if pms (private messages) are truly private? Or are they read by forum admins?

No, they are only visible to the person they were sent to … unless they are reported for spam or whatever, in which case a copy is sent to admins.

I can actually access them via the AdminCP so technically I could read them if I wanted to, but I don’t and never have.
The only time I can imagine it would be necessary was if someone was accused of spam via PM.