I had some mild 'debates' with distant relatives at Christmas. The main thing I noticed among my liberal family members was that they always go back on their education. They use their flimsy major(s) in college as proof that they are somehow experts. Additionally, they always bring up their white collar jobs as somehow proof of their superior intelligence.
They also like to elevate the newspapers they read as gospels of truth. They will outright dismiss any other source, without addressing the argument. Their explanations are often overwrought with big words, and could be said in half the time. I also notice they tend to speak condescendingly when they disagree: they'll say things like, 'you misunderstand' or 'you don't grasp' or 'you lack comprehension'...
They will go to great lengths to parse words rather than to address the substance. It's like I'm talking to a human Snopes...
The most stupid people think they are smarter than anyone else. Annoying but provides lots of wink humor.
See Dunning–Kruger effect referenced above...