It's a media thing, not a leftist thing
Since you haven't ever been subjected to slavering rightist mainstream newspapers, you wouldn't know it to be true.
Neil Kinnock was continually portrayed as a blithering idiot by the UK press in the 80s/90s, while That Bloody woman was a shining example of goodness and light.
Spitting Image got them both right - Kinnock as a rambling verbose dolt, TBW as a raving lunatic. ;-)