I would say that the false veneer of positivity that politically left messaging is drenched in is one of their most irritating qualities.

Sorry to double post, but I agree. It's the unique combination of abject delusion, and the smug, self-satisfied certainty of their intellectual and moral superiority. And by claiming ownership of that wafer-thin veneer of positivity, they imply (and sometimes state explicitly!) that anything opposed to them, no matter how rational or decent, is anti-love, anti-positivity, and irredeemably evil.