People like this really bug me, I'm a Spurs fan (Tottenham Hotspur in the UK, not San Antonio in the US) who makes use of a Spurs message board with other friends (most of whom I know in RL) to chat on a daily basis.
A couple of years ago a guy started posting there, enterred himself into the community and was just another chatty guy for months on end.
Eventually he started asking more and more strange questions and being a typical bunch of lads, mostly in the company of friends, he got some outrageous answers to some of the questions/situations he brought up...
Give it another month or so and suddenly in one of our newspapers in the UK there's an article by this guy under his real name quoting all of the things that he had prompted on this message board trying to paint Spurs fans as evil, malicious, racist and more based upon comments said in a jokey fashion to someone who had portrayed himself as a friend in a group of lads. He literally named people (some by real life names as opposed to online handles) in a public newspaper making statements about their character that he had solicited and which they certainly would never say or honestly actually mean outside a joking scenario with friends.
I just don't see what people get out of things like this and how people can do it in the first place...