Repro figures on repro cards as a concern is getting really nutty... I wouldn't have a problem, but the ads do say "Perfect 1977 Kenner Stormtrooper in C9.8 grade". There's the rub. In a card it looks right to almost anyone. If the ad said " repro stormtrooper" it would be at least honest. If it said repro but didn't mention the stormtrooper being repro specifically if the seller knows, it could wind up off the card and inserted into another collection as a mint real figure.
Here's the bottom line in my humble opinion: These figures exist. If we cannot stop their existence, we must deal with them as being out there. Repros have existed forever. As long as coins have been made, people faked them. We only have to educate ourselves and others as to what figures are possible fakes- so far that list is limited, and most stand out easily. To pretend they can be stopped if a buck can be made is to deny reality.
If one chooses to misrepresent an item, they will. As much as I am not a fan of ex-pres Regan, he had a policy of "Trust, but Verify" which means there is a responsibility to know that people sometimes lie, and while something may or may not be real, if we start with their assertion, VERIFY what they are saying. As much as AFA of a grading body can be detested for various reasons, experts are sometimes needed with the high quality fakes out there.
North Korea has been making counterfeit US $100 bills for over a decade that pass most bank inspection devices. There will always be people who con, and people who don't.
Personal responsibility to be truthful is not enforcable. One must protect their own interests. If I buy a figure and something looks wrong, I investigate further. Sometimes I miss something, it is the risk of dealing with anything that has value.