Not only would the passengers who had paid premium rates for F & J be a bit peeved about people who turn up at check in and make a nuisance of themselves until they get an upgrade, me traveling in Y would be also because it is not in my nature to act that way, I have seen so many trying to beg an upgrades it makes me sick, they are really trying to steel something that would have gone to someone else on merit.
What annoys me is that I believe this happens at some airports as I have had many upgrades, all but one have happened (about 5 times) at the gate when transiting DXB where upgrades are picked by the computer on merit.
At BHX I have had one and BKK had none yet I have passed through these airports just as many times that now I have come to the conclusion that these airports use a list based on the ground handling agents choice, which is anything for an easy life...
BB