I can see that the left/darker one does look unpainted. Shadow Grey is kind of sprue color. But all I did after painting was wash coat. I still plan to highlight/drybrush in such a way to make them look frozen as they come from an ice world. The silver and black parts will look best this way I feel, hence why I wanted better armoured ones to be silver. Aside from seeming somewhat dull, I thought the darker paint scheme might work for Tau Stealth Suits.
"Fetch me another plaything. This one seems to have broken." -Urien Rakarth
Space Marine- "This planet is ours, witch."
Eldar- "No ... This planet is theirs ..."