War of Honor wrote: "We haven't really tried to make our presence a secret—after all, half the effect of a Q-ship derives from the fact that potential raiders know she's out there somewhere. If they don't know she exists, then they're not going to be worried over the possibility that any given merchantman might be her. But by the same token, we haven't exactly broadcast a description of any of our ships, and we've been known to change the paint scheme from time to time. The smart paint cost us a pretty penny, but it was worth it."
"I often think it's more useful to Q-ships than it's ever been to regular men-of-war," Alistair McKeon observed, and several heads nodded. The "paint" used by the RMN and most other navies was liberally laced with nanotech and reactive pigments which allowed it to be programmed and altered, essentially without limit, at will. Unfortunately, as McKeon had just suggested, that was of strictly limited utility for a warship. After all, the distinctive hammerhead hull form of a warship could scarcely be mistaken for anything else, whatever color it might be. Besides, no one was likely to rely on visual identification of any man-of-war, which was one reason most navies also had a distinct tendency to choose one paint scheme—like the RMN's basic white—and leave it that way.
But merchantmen were another matter entirely. Even there, cruisers and pirate vessels alike tended to rely primarily upon transponder codes, but anyone who wanted to steal a ship's cargo had to come close enough to do it. And at that point, visual identifications—or misidentifications, in some very special cases—became the norm.
Seems ship design is unlikely to be an issue for IDing warships, but for merchies it is a factor, especially given that Bachfisch being able to disguise his ship is a non-trivial plot point in War of Honor.