I think the "I'm not good enough" mentality is a real negative thing for things like these challenges.
Of course when you're working on a project, you should be thinking "make it better, make it better" but to be worried or embarrassed about putting work on these forums is nonsense.

I don't think I've ever seen a really nasty comment from this community. Even if you don't think your stuff is any good (and I should know, cause I'm very self-critical), you might get some very good criticism on how to make it better. Things you might not have noticed. I do find it intimidating when the really experienced people are putting up stunning work, but I know I'm in it to learn more, not to win.

So on that note, and never having produced an organic mesh that I didn't think was total crap, I'm going to join this challenge, and you (meaning everyone) should too, if you can spare just a few hours.