Unfortunately, the only Oldsmobile cars that can go completely unquestioned are cars with Canadian documentation. Sadly, all the other paperwork is going to be suspect in one way or another. I would imagine even the Thornton’s could be fooled today because the fake documentation is so accurate.
My friend was a longtime serious W-30 convertible collector and he was bamboozled on a fraudulent 1971 W-30 4spd convertible. He knew these cars well and went back to the 1970s collecting them.
I remember cars as far back as the early 1980s being accurately cloned into W-30s. Now people think those cars are real because they have appeared as W-30s for such a great length of time. I know of numerous cars in the Chicago area that started out life as standard 442s only to eventually become "documented" W-30 cars.
It is too bad that all the corruption and dishonesty has entered the hobby. However, when serious sums of money got involved in the hobby so did all the dishonesty. It would be funny if they ever found the paperwork for these cars to see how many of them today are fakes. I bet it would reduce the W-30 population by 90%.