Can I come at this from the other end, i.e. not evidence or otherwise of conspiracies; but evidence or otherwise for cover-ups or withholding of evidence or the relaying of a self-evidently incomplete picture.
There must be any number of books and articles offering evidence of any of those. And writing those books require banks of researchers to discover what's been hidden, buried etc. We posters can't have our own research team.
So, I could quote Greg Palast (in "The Best Democracy Money can Buy") saying he had in front of him 2 CDs of voters' names, voters who had been purged from the Florida voting rolls. Something to do with criminality, tho' over 90% of them were innocent.
At some point, CBS's office was contacted about the story. CBS called back to say the story didn't stand up. They were asked what they'd done to check. "We rang Jeb Bush's office."
Does quoting any sources with that sort of stuff help with the argument? We'll see.
One more ex.
Astronomy arose out of astrology. And Isaac Newton was an astrologer, amongst other things. Two of Melvyn Bragg's BBC In Our Time learned discussions were about the history of astronomy and about Newton. In the two 40-minute progs., not a word about astrology. Unless you already knew, how would you know there was anything missing. And that's also a question in general.
And many of the occult works of the great scientists incl. Newton, have simply not been translated from the latin.
As I asked once before, how do you know when you're ill-informed? (I include myself). Those would be 'unknown unknowns' - things you don't know you don't know.