I read a great deal. I have read a great deal. I have edited a lot of other peoples' written work over a lifetime.
If you do that, you develop something like an ear for music or an eye that recognizes faces, and troll writings have a particular sound. For one thing, they are often infantile, of poor vocabulary, are unimaginative. In a word, boring.
And I have read enough on the internet to pick out what I am convinced are the writings of bored people just posting for the sake of it--and I believe it is for money, and probably not much money.
Sometime sift through the archives of David Horowitz's research on Frontpagemag.com an you will see that the oligarchs who have tens of billions of dollars would think about as much of a few millions on shill posters as you and I would think of latte money.