I have always thought the term "troll" is cast about too frivolously on line. I have seen people labelled "troll" in comment threads for simply bringing some objective statistical data to an argument. I have seen the term applied to commentators from an ageist perspective. I have also seen comments which have earned the label.
The other day I commented on an article addressed to a gay audience which had been linked to Facebook. The author was a gay Christian apologist for racial violence in Baltimore. The author and some commentators implied that LGBT people frequently used violent protest on the road to gay rights. This was historically inaccurate. The LGBT rights movement has been overwhelmingly nonviolent. The Stonewall Riot and the San Francisco riot after Harvey Milk's homophobic assassin was basically let off were anomalies.
One commentator from London called me a racist because I pointed out the inaccuracy. He then claimed that ACT UP was a violent movement. I corrected this new inaccuracy and shared that my source was my own witness of the events as an HIV-positive person. I will probably not read any further posts from that commentator on that thread. However, I am grateful to him for clarifying the term "troll" for me.