This is the point where I would fairly ask how this “virtually every instance” was determined. And if it was possible to determine, why past associations weren’t then overlooked in favor of this near infallible present determination.
Determined by evidence. Even at the time, the media was lying about what was going and trying to make innocents out of the guilty. An infamous episode was with a Black woman named Annie Lee Moss. She played dumb during her investigation, claiming they meant another person, but it was determined she was a Communist agent working for the federal government.
In the George Clooney movie he did about leftist propagandist Edward R. Murrow, they played up Moss as an innocent (but hilariously and hypocritically, Clooney admitted as an aside in the commentary that Moss WAS guilty !).