I was once called a shill for merely questioning the Rothschild Banking Conspiracy. I merely asked what proof did certain conspiracy theorists had for:
1) the claim that the Rothschilds banking dynasty and family is worth trillions of dollars. (Some claim the Rothschilds are worth hundreds of trillions of dollars, which is about as much as/more than the entire GDP of the global economy).
2) proof that the Rothschilds are secretly controlling the entire globe's economy. Apparently, some people claim that the Rothschilds (and other banking families) secretly cause economic calamities and wars around the globe.
I was called a shill because I tried to show how implausible the Rothschild World Domination Banking conspiracy theory really is.
Then again, I did this on a site called 8chan, on their politics board, which is dominated by an overwhelming majority of conspiracy theorists. Most of the people posting there are conspiracy theorists.
I tried my best in changing their minds, and getting them to stop believing in bunk. But they refused to be reasoned with, and continued to unquestioningly believe in bunk. I didn't use any ad hominem attacks on them, but they certainly did on me. In fact, one of them even tried to unsuccessfully report me to the site's moderators for intentionally trying to spread disinformation aka doing shilling.
It is very difficult to change people's minds, especially if they have the support of group think. Since the overwhelming majority of the posters on that forum were conspiracy theorists, it would have been very difficult for anyone with a non-conspiracy world view to spread dissent amongst the conspiracy-theory-believing conformity. In other words, it would have been very difficult for anyone to change anyone's mind, and stop more people from believing in CT nonsense, let alone change the general consensus of the CT-believing group.