Although it varies in content, reactionary ideology almost always shares structural similarities. First of all, there is the assumption of an already-existing, natural, well-functioning whole, which simultaneously serves as an ideal. Most commonly this is the nation-state.
Then, to deflect blame from this perfect whole, all problems and dysfunctions are attributed to some parasite, some illegitimate invader coming in from the outside. The most obvious example is "the Jew". The idea is: if this parasite was eliminated, everything would be good.
Often, this invader is immigrants in general. But it's used by liberals as well. For example, "American democracy" is the well-functioning whole, and the only way it can allow a president like Trump to emerge is because of an outside invader - Russian interference.
Or, of course, the more recent "outside agitators". The very fact that specifically an "outside" agitator is taken to mean something automatically bad and illegitimate, presumes that the "inside" is an otherwise self-enclosed and well-functioning system.
This serves 2 purposes. 1: It pulls attention away from problems internal to the system, meaning that nothing fundamental needs to be changed. 2: It substitutes all the various fears people might otherwise have with just one, concrete fear: the outside invader.
Žižek has pointed out that, because this "invader" must serve such a big function, it must be identifiable anywhere and in anyone, and so is given contradictory descriptions, so that anyone could be accused of being one. Again, "the Jew" is the most common example.
In Nazi propaganda, the Jew was simultaneously identified with typically "bourgeois" features: greedy, rich, scheming, exploitative; and at the same time stereotypically "proletarian" features: dirty, uncultured, promiscuous, spreading disease, etc.
Try to identify these features in the ideologies you notice, and you'll often easily be able to. I'm remembering also the "Antifa" figure used by conservatives: easily offended, weak, cowardly, pampered, but simultaneously thuggish, aggressive, violent.
