Well, I will say this.
I think sometimes collegians have better bullshit detectors than alums and can probably realize who is there because they really love doing it, and who is there because they want to get AIed.
In my experience, most non-members who volunteer with collegiates are faculty or university staff (grad assistants, etc) and are there because the school requires faculty advisors. They are usually pretty sane.
If Rhoda Random from 3 towns away with no connection to the sorority OR the school had contacted our chapter about advising, I think our school would have put the kibosh on it before it even got to the level of the sorority approving it, just for safety reasons.
I'm rereading and realizing my post was misinterpreted. I don't mean a PNAM should contact a college chapter and volunteer w/ collegiates first. I mean that unless you're an alum of a local sorority or a GDI who worked in the Greek Life office, you shouldn't get AIed and then immediately jump into a role like rush advisor.