I think I know how this works.
For personal context, before I went to the '98 Burning Man festival, one of the things I'd read from a couple different journalists was that "everybody" runs around naked. Which, fine by me, I'd already spent a lot of time in clothing-optional spaces, I'm not fanatic about it but it's nice.
So I got there early and set up a public shade structure on one of Black Rock City's main roads and spent most of each afternoon just watching the crowds go by. I don't remember seeing more than one actually naked person the whole week. I think a topless woman passed by my intersection maybe every half an hour, sometimes once an hour. So why in the hell were people, normally pretty smart and observant writers, coming away with the impression that everybody was naked?
Then I remembered an unrelated passage from Joel Garreau's great book about the history of the outer-ring suburbs, Edge City. Mall developers told him flat-out that they tried to keep the crowds in their malls less than 5% black. Not because they themselves were racist, but because they had determined, experimentally, that if more than 5% of the people in the mall are black, the median white shopper will wrongly describe the mall as at least half black, as mostly black. And not a few of them would describe it, at 6% black, as a mall where "only black people go." Why?
Because, emotionally, they were still upset over the last one when the next one came into view.
Same as the journalists describing Black Rock City as all naked. Same as the right-wing religious culture warriors describing television as entirely mixed-race and gender non-conforming. Not because it's even vaguely true, we know that, but because they haven't gotten over their discomfort over the last one by the time the next one comes along. The anger, not the stimulus, is the part that's continuous, so their mind lies to them that it's "all" the thing they can't get over.