Probably one of the most valuable and surprising things I've learned studying history over the past few years is the concept of "Deep Lib Slop".
"Deep Lib Slop" is the effect of elite liberal propaganda on power, politics, and history before computers.
Elite liberal propaganda was influencing vaunted figures like Sutton and Quigley and coloring their analyses, too.
It's very old & used to be much more tribal than it is now even.
It's hard to describe, but you can develop a smell for this.