Void's right, I didn't know what he was talking about at first but after looking at the Nucleus props there's some pretty obvious paint patches, scratches etc.
In fact you can see what he means by looking at the bomb cart in his sticker.
Basically just spice up the blank areas. Slap some stickers, water stains, scraped paint, nuts and bolts, hatches, wiring, metal patches, Hell, maybe some bird shit. Why not?