Surely nobody would cheat for a different coloured username (as others have said)?!
I'm going to make sure I enter every comp from now on as I see it as a great way to do something I wouldn't normally do, out of my comfort zone (I'm a slow, methodical modeller) whils having a bit of fun. Similar to Box, I've never seen it as a competition per se, just a chance to do something different, if you get a purple name, cool, if not, you've had fun and done something different for 30/60 minutes.