It's not hardcore collectors that we're referring to, it's people that have multiples of the same item, or (and I'm not saying this was you, Starwarsgrapher) people who cut in line with an item that they'd conveniently "forgotten about". It happens a lot at cons, and yes it is rude and annoying!
i understand the cutting part, that would bother me too, but you are a show where you are paying for someone's signature. it is no one business how many you have, how many of a particular shot or how many items you have. if you are paying, you get them signed. it's that simple. that's what the celebrity is there for. they are there to sign autographs. i have been going to shows of all sorts since 1981, and that's the way it's always been. if i attend a show here in the states or in england the guest is there being paid to sign. i am the attendee and there should be no qualms in paying that person to sign. i have had to wait behind many people in my life who have gotten 1, 2, 3 or 50 things signed. i just waited my turn. it happens. at this show, i stood behind another collector who asked question after question after question to a few of the camera crew guys. each time, i waited my turn. i was fine with it. it happens. i realize there are 1 and done people that attend the shows, i'm just not that guy nor are my friends. i was there to accomplish getting my items signed by these guys and i'll always do that at every show i attend.