This doesn’t answer your question but is more of an interesting observation that fits your question. It seems bar for political leaders’ mistakes has gotten so low over the pass few decades.

In the early 90s then VP Dan Quayle misspelled potato (though apparently not 100% his fault) and he was labeled an idiot by the entire country. Bush had a lot of funny Bushisms but most are either weird, poorly worded, malapropisms, or a mix of all three.

Then you have Trump. And while there are definitely people who think he’s an idiot, it doesn’t seem as widespread of a belief as it was for Quayle or Bush. I think part of it is because Trump is far more sensitive to criticism than any president we’ve seen so he’ll go after people who say anything negative about him. But I’m sure there are other reasons as well (ex: politicized news channels, social media, technology etc)