Some are so sure of their world view that they just assume their conventional wisdom is correct about specific subjects that they clearly (to someone who has) have not studied. I know I was back in 04 when a friend mentioned something to me that I thought was absurd, but is now common knowledge for anyone understands F=ma and has checked that specific fact (that I'm deliberately not mentioning). For example, look up the art collection Skippy's brother keeps, or that shop owners (now hidden but thoroughly archived) Instagram account.
"Fact checking" sites are about as unscientific as it gets. They have two obvious flaws, first they generally only "check" facts they can "debunk", second, they often frame what they are checking in a way that lets them use a corner case.
The right way would be to just list data, things others can independently check and allow the reader to draw their own conclusions.