The only instance that was close to a successful scam was the fake pikachu snap card. They took a real psa label, and put it in a GMA case with the fake card. Someone agreed on a trade for a real trophy pikachu + cash. Luckily it never went through, thanks to this thread.
Fake cards are nowhere near the real deal. Even in the worst case hypothetical where a grading company makes a mistake, E4 can identify the issue. As we did in the thread above, and this recent thread as well.