Internet “Trolls” who come into private groups and message boards do so with a single goal in mind, to fatigue and/or bore honest contributors in hopes to prevent them from contributing. Their tactics amount to the internet version of a “heckler’s veto”. They hope to take over your message board or private group by driving the good people away. Their tactics are almost always the same.
At first they start out civilly, they claim you are wrong and might post an outdated piece something with an anonymous source from the NYT or WashPo or an unverifiable opinion piece from a smear outfit like Think Progress.
When an honest contributor then posts superior evidence such as on the record statements, court documents etc, such evidence filled pieces are a bit more complicated, as it always takes more explanation to unravel a lie, then it does to simply make a dishonest accusation.
The Troll will post laughter, call someone a liar and then post again the same accusation or inferior evidence piece again, without actually responding to the specific points or evidence made by the honest participant. The Troll simply goes on as if the superior evidence was never posted in the first place and keeps repeating the same debunked nonsense in hopes of fatiguing honest participants into just abandoning the thread and going away. The Troll will also hope that readers of the thread or group will not take the time to read the entire thread carefully, fully understanding that the honest contributor will have longer posts most likely skipped by lazier readers because, as pointed out earlier, it takes more space to unravel a lie than to simply make a bogus accusation.
Then the Troll goes into rinse & repeat mode: tell people that they are liars, and then when faced with superior evidence otherwise simply ignore it, repeat their original assertion and/or make new accusations, throw in some virtue signalling – and THEN in the ultimate act of chutzpah, once the thread gets long enough, accuse the honest participants of not posting any evidence.
Eventually, someone calls out the Troll on their tactics and blasts their behavior. This is when the Troll calls for an administrator and pulls the victim card, claiming that the honest posters are being uncivil and picking on them rather than posting evidence. If said administrator does not read the whole thread carefully to see what is going on, they fall for it and scold or ban the honest contributor.
It gets better, the Troll will often start a new thread on the same subject complete with the same anonymous/debunked claims to start the cycle over again.
In thread after thread, the Trolls will do this over and over and over again until honest participants just move on for good, essentially all but shutting down participation in your group.