I guess it's down to what the competition is seeking to judge?

e.g. modelling skill, rigging skill, composition skill, lighting skill.

I guess it's easier to judge, in many ways, if they just define a blanket rule that only original meshes can be used in a render.

Although, I still think unless you award marks in each of the above categories, methodically, you're likely judging apples against oranges... and both against cheese ;)

The "art establishment" (or rather those that seek to create such a thing) always seem to fall into these sorts of traps though, I guess.

the above is a highly subjective statement on my part, masquerading, unconvincingly, as an objective one... I suspect ;)

But anyway... the notion of art... and what makes good art... is so subjective.

Any organisation, body, academy, panel setting itself up to judge artwork... to make criteria for the acceptance of artwork as being valid... whether that organisation is the Ecole des Beaux-Arts or the CGSociety, or some group on DeviantArt... should, IMHO, always strive to remember this fact...

...I would have ticked the waffle advisory box for this post, but couldn't see it next to Language, Violence and Nudity ;)