Yeah this has happened a couple times to me. It's annoying. This guy who was a mod left and we demoted him. He came back, asked for his mod position back and we said no, because he left without notice. He left again.
I had a person ask to be site staff after she spammed up a whole section and then she "helped" by copying something she found on another website. It warranted her a "site staff" position or so she thought. Bah children these days, eh?
It has been done to me once. But that was when I needed a moderator, I did give him the job and so far from the moderator log he hasn't really done much on the forum.
I've had that happen to me, I would never hire or promote them. Why? Because I want to make sure you get along with my members and staff, I want to make sure you can follow the rules and that you are able to be an active poster. I don't know what kind of poster they are and if they will help create the atmosphere I want on my forum.