The Elite Trooper head definitely looks like he's scowling compared to Rex. I wonder what it would look like with the photo real paint apps?
But I've got my Bad Batch clones here at my desk. And lots of the lines on the face of the Elite trooper match up with the Captain Grey figure I have next to my laptop.
Were you see scowling, I see constipation. 
It's hard to get all that armor off. After constantly holding it in for hours, you would self constipate too.
And now I'm wondering if the green milk on Ahch-To is actually space immodium???
