I first caught on to this being a possibility a few years ago, when noticing the trend of commenters on articles and forums. When Hussein Obama was elected in 2008, they were all over the place, but they were actually passionate and seemed to be true believers. They were very easy to dismantle in an intellectual discussion or debate, but they would fight and try to sling talking point after talking point, no matter how false or debunkable. But, you could at least corral them if you were persistent, eventually boxing them into a scenario where they stop posting, or more satisfyingly, go into a complete meltdown.
They were at least passionate humans that you were affecting. Some off duty barista wearing a hope-and-change Che Guevara shirt was screaming at you while posting, as his poor laptop keyboard (manufactured by an evil corporation - that always got them) took the brunt of the emotion you conjured from his inability to intelligently retort. When he biked to work on a bike manufactured via free market capitalism on a road built by taxes stolen from people who work for companies, he was thinking about that thread where you handed his ass to him, muttering "George Bush", "Halliburton", and a few other classics, until he got to work, where he made coffee and lattes with machines built by corporations, serving people who can afford $5 lattes because they work at corporate or small business jobs, and ringing up these customers to add more to the bottom line of the global corporation he works for. Life really sucks when you're a Marxist.
Eventually, they seemed to die down. As Hussein Obama continued his attempts to transform the country, the intensity of his support dropped off. I saw stories like Hussein having to raise foreign money, fake Twitter followers, and others that circumstantially seem to show there is not as much support for a candidate (not just Hussein Obama) as one might think. They seemed to just collect at the common Democrat-based forums, but weren't venturing out to non-liberal sites like they used to. I just figured liberals eventually became less enthusiastic about their Marxist positions.
Smash cut to a few months ago, if you didn't know better, you would have been certain Trump had an overwhelming base of support. I thought this was odd, and didn't make any sense. If you posted "Hi", you'd get 20 replies posting lies about Ted Cruz and how Trump is going to build the wall. I was happy, because it meant the passion was back from 2008, but it turned out to be like punching a zombie in the face. I would post a cogent reply, and I would get a completely unrelated reply back, as if some AI program was parsing for certain words. I then figured these were non-human post bots, or dumber, paid trolls. I always joked about paid trolls, but honestly, I really didn't believe it, but it was always a joke to explain how liberal idiocy can stay alive on the internet.
Then, I see this today. This apparently really does happen! This is the only story I know of, but it sort of reinforced my gut that kept telling me about internet trolls. Their only job is not to discuss or debate, but to spread propaganda. I have been posting since late 2008, but I haven't met a Hillary Clinton supporter online. Ever. I figured they were like space aliens; I'm sure they exist, but I've just never seen one. Now, I guess we'll see a few.