Thanks! A lot of it is just in the composition of the screenshot - lighting and background, etc. I take a lot of screenshots just to get a few to post.
I think I'm the only one who uses light-colored rivets on bare metal skins (though I do use dark rivets on the undersides of wings and stabs). A while back I started doing a little trick with rivets in the spec files for bare metal skins:
While my rivets are light colored on the diffuse map, I make them quite dark on the spec map. That means while they normally show up white, if the sun glare catches them, the low spec value turns them dark compared to the surrounding bare metal. So when you pan around the skin externally and play with the camera/sun angle, you can see the rivets turn light to dark as they go into a patch of glare.
It's a subtle effect, but looks fairly realistic I think, and makes the skin a bit more dynamic and reactive to the light angle. Seems to work especially well on the Jug's big fuselage sides...