So, by this I'm to understand that you will read private messages with probable cause? While I respect your position (and think highly of how you conduct yourself with your responsibilites), I'm definitely not ok with this.
As Maged mentioned, I usually only confirm that a reported PM is accurate. Sometimes I read all of the PMs between the potential scammer and the victim, with the victim's permission. There have been only a few cases where I've read all of a potential scammer's PMs, and they all turned out to be guilty in the end. I don't do it lightly. I never read random PMs; I haven't even read any of Satoshi's PMs, which would undoubtedly be very interesting.
No actual shit, dummy, why wouldn't an administrator have access to PMs? Even if you designed a system that had no easy GUI to do it, you could still read them with a proper commandline SQL query, it just would be a little more difficult. I can't believe you would think otherwise.
It is necessary to use SQL to read them. SMF doesn't have an interface for it.