Quoted from CaptainNeo:
B/W games I call it fogging. And it wasn't the primer that caused it, it was the clear itself. Until the past 15 years or so. clear wasn't clear. It had a faint foggyness to it. Just the way the clear was. Todays technology clear is crystal clear. Trying to duplicate that foggyness is very difficult when you need to match chipped out clear on old b/w games.
Close. It's the primer that's below the silkscreened art. Tear a PF apart and you'll see...sand it down to the artwork. Sanding off the clear won't make the inserts clearer until you get beneath the art.
Or just look at EMs/SSs. Frosted, and they don't have clear on them at all.
Doesn't really matter, though - it's not a problem while ghosting may become a problem over time.
Ghosting, even being more or less expectable, is a defect. Something is coming apart.
Inserts are not frosted any more due to newer primer technology, so I do agree that it's technology that leads to this difference.
It would be interesting to know if the Stern PFs with problems are primed at all. Due to the clearness of the primer it would be very hard to tell. But that would explain a lot when it comes to lack of connection between plastic and clear.