... sometimes when one gets them looking too realistic, the characters enter the feared 'uncanny valley' ...
The Feared Uncanny Valley -
I think I know what you mean, like when the image not only is super-ideal in form and substance, but the texture details also have the complex light and random imperfections of reality. So much so that you stare fascinated at the image so long you forget to be aroused - and surprisingly find yourself back in self-awareness minutes later.
It's debilitating, and confoundingly unfappable.
Strange, huh? You'd think it would be the other way around, that the faker stuff would be harder to approach.
BTW - I agree, Rick J consistently finds the perfect balance, always a total turn-on. A natural CGI genius.

-D'Artagnian