Most "imperfections" in a metallic surface would actually be rendered non-visible by high-intensity reflection of lighting. So adding them anywhere would not make any sense.
Any highly obvious panel bevels for example, would be made harder to see by the reflection of the surrounding material, and at the right angle, the bevel itself would be "filled" with light as well.
(A good example of this would be the Space Shuttle bay doors. The seams for each segment are almost impossible to see when it's sun-ward facing unless you are up close, but are highly visible on the moderately shaded side)
Dirt and grunge would still be visible, but might became muted. Not because of the underlying material, but again because of the surrounding material saturating the area. This is especially true for any super-reflective material (non-painted or coated metal (especially if it's polished), any polished painted or coated surface (most notably any non-absorbing color) or glass (especially mirrored))