How do you know if you're listening to a demagogue who probably doesn't have much that is useful or rational to say? Here's a hint: If you see or hear someone say something along the lines of "Democrats are lying, evil socialists who just want to give the country away to illegal aliens and unwed mothers," run away. By the same token, if you hear or see someone say something along the lines of, "Republicans are lying, evil fascists who just want to give the country away to the rich and big corporations," you should run just as fast. It is unfortunately true that these are two of the loudest groups on the internet, but they are both ridiculously wrong and, quite possibly, irredeemably stupid.
There are those on the right who champion ideas that are dangerously close (if not completely over the edge) to fascism, theocracy, aristocracy, or some other form of totalitarianism or near-totalitarianism. There are those on the left who champion ideas that are dangerously close (if not completely over the edge) to socialism, communism, enforced utopianism, or some other form of totalitarianism or near-totalitarianism. Most of even these people, however, do not believe or realize that they are promoting totalitarian ideas. They honestly believe that their particular approach will promote the best good while steering clear of the potential pitfalls. Does this mean that should not be opposed? Absolutely not! The best intentions can lead to the absolute worst results precisely because the person or people following them believed he, she, or they were doing good and were thus blinded to the actual results. If without blindness, there is always the danger of "We're too close to turn away now." Besides, the best reason to oppose people who are doing harm while truly believing they are doing good is because those are exactly the people who might come to see their own error. If their goal is to achieve a certain result and they can see that their actions are going in a different direction (and if they are truly motivated by their claimed goal) then a rational dialogue may cause them to change their actions. Demonizing them without that rational dialogue, however, is not likely to achieve this.
There are also those on either end whose goals are the very things that would and must lead to some form of totalitarianism. More often than not, this is because these people are actually arrogant enough to believe that their form of totalitarianism is for the good of humanity. Obviously these people must be opposed, but rational dialogue won't usually accomplish much. All we can do with them is fight and prevent them from gaining the power they so desperately crave.
Neither of these conditions, however, describe the Republican or Democratic parties, nor do they automatically describe voters who identify themselves as Democrat or Republican. It is certainly possible for voters in either of these parties to fall into one or the other of these camps and it is equally possible for politicians of either party to do so as well. It is not, though, a defining aspect of either party. It is just as possible for members (whether voter or politician) from almost any of the various independent parties to favor (intentionally or not) policies that lead toward some form of totalitarianism.
I, an independent, know many people who label themselves either Republican or Democrat. Not one of these people knowingly favors any policy or plan that would lead to totalitarianism and not one of these people would be opposed to removing his or her support of a policy or plan upon seeing evidence that it would do so. We may (and often do) disagree on many particular points, but not that one. That one, to me, is not negotiable. I would not knowingly or willingly associate with someone who favored any form of totalitarianism or who refused to remove support from a plan or policy after seeing that it would do so.
Republicans are not inherently fascists and Democrats are not inherently socialists. If you see someone claiming otherwise then that person is the one spreading hate and lies, and should be treated as such.