It takes a different kind of critique, is all.  It's more like commenting on a quick sketch, than a painting.  Form, balance, and execution still apply.  If it's a piece of crap, then whoever posted it needs to be chided as wasting our time.

If it has potential to be turned into a good render, tell 'em what might help 'em do that.

I use 'thrown together' to show-case something new I'm trying, or using and NOT sure what I'm doing.  Comments positive and negative help guide the useage and execution, IMVHO.

I cannot save the world. Only my little piece of it. If we all act together, we can save the world.--Nelson Mandela
An  inconsistent hobgoblin is the fool of little minds
Taking "Just do it" to a whole new level!