|Someone is wrong on|
A concern troll visits sites of an opposing ideology and offers advice on how they could "improve" things, either in their tactical use of rhetoric, site rules, or with more philosophical consistency.
 Typical fomulation and tactic
A typical formulation might involve the troll's invocation of a site's espoused ideals alongside a perceived example of hypocrisy (such as contrasting "we value free speech" with the banning of a "dissenter"), and with a call for some relevant reform by the troll. This reform will frequently be burdensome or silly - the concern troll's message is: "I have some concerns about your methods. If you did these things to make your message less effective, it would be more effective.". Surprisingly, there are people who spend so much time on the Internet that this is actually a thing they worry about.
One common tactic of concern trolls is the "a plague on both your houses" approach, where the concern troll tries to convince people that both sides of the ideological divide are just as bad as each other, and so no one can think themselves "correct" but must engage in endless hedging and caveats. This preys on a willingness to debate critics and allow dissent; everyone wastes time discussing the matter and bending over backwards, so as not to appear intolerant of disagreement, all to the great amusement of the troll.
 Popularity and history
The term's popularity originated on Daily Kos (though the term likely predates their usage). Historically, there have been many figures considered concern trolls, although generally the formulation of the label was rather more elegant; for example, Henry VIII called Martin Luther a "horrid and furious Monster" unleashing "Stings and Poisons, whereby he intends to infect the whole World."
The danger, of course, is that not everyone with a concern is a concern troll - and not every concern is unreasonable. In environments of genuine groupthink, applying the concern troll label may serve as a means of enforcing conformity and punishing (or silencing) dissent. And even without actual groupthink in play, many Internet posters find dismissing an argument much quicker and easier than evaluating it. In addition, the term "concern troll" focuses not on what the person is actually saying, but on some alleged "secret real agenda". Thus, it is the perfect refuge for someone who has no counter to the actual argument: simply ignore the points made, allege some other position, and then accuse the other person of lying if they deny that that is what they're really saying. It's a combination of strawperson and argumentum ad hominem: make up something to attack, and ignore their actual points on the basis that since the points were made by someone acting in bad faith, they need not be addressed.
Sometimes outsiders will come by and make concern troll-like statements sincerely. Some are sincere but stupid. Some may be sincere, insightful, and justified iconoclasts, merely making valid observations unwelcome to the dominant ideology or culture of the forum (the Cassandra syndrome). Often, of course, the person is misguided, wrong, and not actually trolling.
 See also
- Agent provocateur
- Deep cover liberal
- Deliberate offence
- False flag operation
- Just asking questions
- Poe's law
- Useful idiot
- Concern troll Urban dictionary entry
- ↑ http://www.dailykos.com/story/2006/5/23/23539/8255
- ↑ http://www.dailykos.com/storyonly/2006/9/20/12307/9839
- ↑ Among Wiktionary's list of references, the Daily Kos one comes first chronologically, despite DK having even earlier references
- ↑ Assertio Septem Sacramentorum. Henry VIII of England. New York: Benzinger, 1908. pg 157