Generally, many of these contents are clique based, but at times a good outfit and a witty reparte can influence votes in your favour. But consider that, at the heart, most of these contents are designed to attract newcomers to a locale, and only one person can win. Do you reward your regulars? Do you allow a free-for-all vote which might just end up a popularity contest? How do you control other's people's choices in a vote process? What's to stop them from bringing in alts, locking them into a dance together, and voting on the behalf of the prime account?
You can't. So just shrug and don't worry about it, and don't contribute Lindens to a contest that might be rigged / unfair. That's always the best option. I go to them, when I do, because a friend is going, and it's a good place to meet new people. If I win (never), I've won. It's more important, to me, that I had fun.
But I agree. The winners, at times, have crappy outfits on, and lackluster AVs they haven't changed since 2008. It just proves that even in SL, beauty is only skin deep.