It is mostly about the visibility of the creature's key points. So if you have everything else done, you then need to pay attention to your focus. Playing at a higher setting makes the focus vastly more visible, so just wait a moment or two for the autofocus to right itself and the score will be much much higher.
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I play on high settings but the focus isn't super visible. Even if I hold the shot for several seconds to make sure the target is in focus, stationary and posing at me I still get slapped with a big ol' C. Do the feet count as a 'key point'? Should I be cropping standing subjects from the knees up or trying to fill the frame head to toe?