anyone can be a troll. Even a long term well trusted member could be a troll.
I've told this story before but I will tell it again as there has been a development.
I moderate on another website - a community type site with message boards and games and a realtime chat facility. Just after I became a moderator I discovered quite by coincidence that a long-term, well trusted member who had previously been a mod herself had what was suspected to be two accounts. On doing a lot more digging (I had to be certain I was right because of how well known she was etc) it transpired that she actually had had four personas on the site. One of them was her, who she really is etc, but the other three all had or had had severe illnesses/disabilities, and, worst of all, one of them had died and her death had been announced on the message boards of the site, causing a lot of upset to users who had befriended her, some of whom had formed quite close friendships with her.
So I banned all of them, but one of her personas she kept up on twitter because it had some other followers...
Occasionally I would look at this persona's twitter feed, she seemed to be doing normal things, but she also was frequently in and out of hospital, had surgeries, was very ill and then recovered etc. Tbh I was expecting her to die, because it just seemed to be heading that way. Then this weekend I was bored and had a look to see if she was still there, hadn't looked for a while, and from a couple of weeks back there are all these messages saying "RIP @) so it would appear this persona too has been killed off leaving some upset people behind.
I have since learned that she also did the same on another site and created a persona whom she killed off.
Talking to her in her normal persona she seems normal enough, and of all the people to be trolls I wouldn't have had her down as one.
Some people are just bloody sick.