Liberal and dumb generally go hand in hand.
Is George Soros "dumb"? Or just misguided politically?
There are extremist idiots on both sides. This fool wants to hug it out with ISIS, total moron idea. but at the same time, you can't throw a rock without hitting someone who would literally drop nukes on 1.5 billion muslims, who truly believes that's the only solution to San Bernidino shootings.
So really, "liberal is dumb" is 3rd grade level thinking that one would scream at a Trump rally. In reality, it's true there are delusional extremists on both sides, on both far right/left bases, and they're misguided as shit.