Am I the only one who hates that talk of "sort of GGL", "types of GGL", that seems so ubiquitous in this thread?! I'm not a sort, I'm not a number, I'm just me!

As for what you describe, those people have been around for a long time though often at specific times (at one point it was every Wednesday etc). As you say, it is not unusual to get some people contacting you at one point or another by email asking if you'd be interested in saying hi. Regardless of whether you meet them occasionally or often, some of those people will remember you very well (I suspect that's part of the job unless I'm particularly interesting to listen to which I don't think!). And no, I wouldn't assume you have to be a special "type" of customer to be approached as I certainly wouldn't have thought I'd be of huge interest to any airline, if only because I'm perfectly open about the fact that I fly many of them depending on my needs rather than indulge in some silly itineraries or expenses just to be on a specific carrier where it doesn't make sense for a given trip (not to mention I have plenty of criticism to convey to any of them!).