Yes, I’ve dealt with rent-a-mobs. One was financially underwritten by a left-wing environmental group and flown in from San Francisco. They had their own professional movie crew with expensive cameras and boom mikes to capture their outrage for posterity (and for the next save-the-world-from-evil-environment-destroyers fundraising campaign). You need to be careful how you deal with them. They will be in your face and taunting you and yelling all sorts of obscenities, but they are actually wired for sound. If you react, they and the camera crew will record it, edit it to take out what they were doing to cause the reaction, and then you get to be on the national nightly news as an evil person.
So when I saw what was going on at the Trump demonstrations, it was all quite familiar.
20+ years ago I was in college here in NJ and some Turkish friends were preparing to go to some Turkish cultural event in NYC. They had a few large black guys with them wearing red Guardian Angel berets. When I asked what they were for, they said they expected some Greeks and/or Armenians might show up and make trouble - so they were basically bringing a security detachment that nobody would mess with. The blacks guys were very well-mannered, but looked like they would eat you without batting an eye.