Scratches actually work fine on a space fighter, in fact if you check out show's viper renders you'll see quite a lot of them. But they're always strategically placed - like I said before, try to think of logical places where they would occur. I do agree that they can't be dominant over other types of damage.
Also take care that you orient them properly, and play with color and density till it looks right. You might also expect to see some paint chipping along the surface edges, and dirt and grime all over the place, with black exhaust marks near the engines, service ports, guns..
Basically it boils down to this - you have the raw skill, but your texturing principle is too random; when you're adding weathering to your texture try to think of the process that lead to that weathering to occur - for instance, if the fighter was flying straight and got hit by a micrometeorite how would the damage be shaped and oriented etc. Having scratches at an angle of 90 degrees to ship's default flight path doesn't look too good, for example.
You might also expect the painted on stripes and text to have faded in some areas, or see parts of it scratched off (btw purple looks horrible imo - viper for pimps?
)
In short, think of what happens to it as it flies and try to add damage and weathering in some sort of logical pattern.
