You can usually tell because they ask questions and they ask the right questions. I've made great progress with fence sitters. The only time I ever plan to argue with a moronic, willfully blind voter is in the presence of a listening fence sitter.(That's when you battle those idiots.)
That has been my experience as well. There are people who truly do not know what is going on and either haven’t the patience to sort it all out, or are so far behind the facts they just need someone to spell it out for them. Those are the ones I engage with. The others, they can rant all their crazy sh** all they want, I’ve gotten to the point where I either challenge them (if I’m in the mood to tangle) or I just laugh at them.