they're relentless!! i had one like this recently on a youtube brexit/refugee vid. most of the lefties who voted to stay in the EU try n paint all of the brexiters as racist. to them this was, literally, a black and white issue...you're either for staying in the EU and opening our borders up to anyone or you're racist.
i tried to question one of them but ended up being attacked by two of them. but they couldn't muster a cohesive argument between them, just regurgitating whatever they'd picked up from MSM.
but one of them was totally relentless, i must have got 20 messages...all with nothing to say, When i eventually got fed up, i messaged him implying that he was sexually aroused by my intellectual superiority and demanded he reply to me like the little b*tch he was....needless to say i had the last word in that particular debate :-)