Okay (backing away from the sensitive subject...)

The impression I've had is that airlines determine upgrades primarily on ff-status, followed by fare basis, traveller profile & appearance, not necessarily in that order. The wild card that beats all the others is individual airline employee's discretion.

The last time I was upgraded, the check in agent made a phonecall to someone else, stating that there was a note that she should call when I checked in. After a brief conversation (and without my requesting anything) she told me I was being upgraded & gave me my boarding card. My guess is that I was upgraded thanks to my ff-status/profile.

So keep flying Justin - the Gold card/1K etc ffs are the ones who get the most upgrades. (and Catman, of course)