People just have different preferences. There's no way to get a result in such a vote that everyone will agree on. If this were the case there would be no point in having a vote to begin with. And after all, this whole contest is just for fun. The winner doesn't get anything from it. I don't see why anyone should cheat here. And even if some people would do so, does it really matter that much?
And concerning the quality of the entries... You really need a lot of experience to get creative pictures without editing anything with additional software. It's not that easy to move several objects consistently, for example, to position a character off-centre. If we applied strict standards, maybe three or four entries would qualify at all. That would quickly end the contest completely.