I suppose one scenario might be, what you could call a "frankensaw". A bunch of pieces and parts left over from repairs, still good, but officially, they got scrapped out. All you have to do is remove the plate, switch the computer module out for one that's unregistered, and New Saw!
Now, most manufactures know repair people do this, they make a frankensaw for personal use, shop use, a loaner, whatever. Strike the serial plate off of it, etch a few of the key parts to say "scrap", then make damned sure you don't sell it. Or that anyone you give it to knows not to sell it. Because if some crazy pile of parts ends up on the bench of some other repair monkey, and they've got a seemingly legit serial number on something, warranty claims is probably gonna freak.
For instance, Peg Pergo makes these little electric cars, that 5-12 year old little monsters drive around and bash into things. A tech I knew got talked into servicing these things, and they were desperate enough to pay standard 1 hour repair rates, because shipping on the things would've been a nightmare. Prices on parts had to be just about what the factory paid. Cheap lead cells, cheap motors, high current rocker switches, heavy gauge wire, all sorts of cool pieces and parts.
Of course, they were BULKY pieces and parts, and scrapping out a chassis filled 1/3rd of a dumpster. But, once in a blue moon, someones grandkids would want one. So, why not make it so non-standard, that it's obvious the damned thing is a chop shop special. 18 volts driving the motors instead of 12, heatsink fins on the motors, 2 motors per gearpack, an insane amount of epoxy, halogen headlights, a real car horn, and the battery compartment just crammed. Required a very non-standard charger as well. (24v 10 amp)
Maybe did 3 of em with crazy mods, and the rule was, once it fried, or got done being used, it goes it the dumpster, it doesn't get sold in a yardsale, unless you wanna get sued.
Similar thing with various other electronics. Car stereos, S-VHS edit decks, Aiwa all in ones. Remove the serial numbers, permanent marker saying "loaner", "shop use only", "Scrap", etc. somewhere on the back, or underside of the unit.
Just about every repair field I know of had something that was officially scrapped, but in daily use. Course, if it's not marked, someone "borrows" it, and then pawns it/sells it on craigslist, then there's problems.