As for me... when hosting a contest, I usually state what I'm looking for. For example, a few nights ago, I hosted a contest on Triumph where I asked to see people in Vanguard or Cimeroran costumes. I also provided a secondary prize for the best other costume around.
When judging a contest, I like to look at secondary costumes (if availiable) and the info people put for their backgrounds. But first and foremost, I state right of the bat what I'm looing for. It seems unfairly arbitrary to not have something in mind, and if you see something outside your parameters to award it accordingly.
I run a contest at random at least once a month, and yeah, I am sometimes looking for recruits for my SG. Being called the League of Extraordinarily Well-Dressed Gentlepersons, it's a natural recruiting area. And I must say, from that Roman/Vanguard contest I found a great new member to the SG.
Hope this helps for the OP.