While their contributions are invaluable, let's be honest, many historians are notorious for fabricating some of the craziest things. Yet many of these lies nonetheless come through and end up as established facts. So here are some questions i believe would be crucial:
Historians rely on primary and secondary sources to form their arguments. Careful, critical readers "consider the source" and check to make sure there is some credible evidence to back up the author's claims.
In your post, you make several unfounded assertions, the main one being, "many historians are notorious for fabricating some of the craziest things" (source: your post.) This is an unfounded assertion because you give no examples or references that can be checked. If you were an historian, that would be called "not doing it right" and you would be duly ridiculed by your peers.
On the other hand, your post itself could be treated as an historical document (a primary source, in this case) by someone working on a thesis about, say, the level of critical discourse on Reddit, circa 2017.