You bring up a good point, vampirate. Anime cons were the first places I saw judging take place at times and locations outside the green room before the show. It took me aback, and it still kind of bothers me because, like you say, some costumes you just don't want to be in all day, and if you have to get makeup and stuff on and lug yourself down there at 10 am to get judged, and then don't know what you're going to do the rest of the day until the show...that doesn't sit well with me.
But I also understand that sometimes there are limitations on space and/or time and that's the best way they've worked out having to deal with it. Unfortunately, any contest like that is one I probably wouldn't enter, because all my competition costumes are too involved to put on/take off/put on again or wear all day.
Maybe that's part of why sci-fi con contests seem more hardcore? Because most of them have workmanship judging right before the stage show, so people are only in their costumes for that block of time, therefore they whip out the most hardcore designs? And by contrast, anime cons set up judging willy-nilly depending on the con's needs, so people are kind of handicapped from indulging in their most amazing ideas. I'm all for having the contest run in whatever way is easiest and most convenient for all involved, judges, directors, con staff, and participants all together, but at the same time, it makes me wonder if that might not be part of the problem. As far as encouraging more hardcore, competitive costumes at anime masquerades goes.
Guess there's a lot of facets to it, to explain why it does seem that sci-fi cons get the more extravagant costumes in competition. So far, I don't think anyone has disagreed with that generalization.