While today is my first visit to this forum, and my second question to review, I do have some insight that I think would be helpful here.
The term Troll has a specific meaning in an online context, which is very different from the fairy-tale troll under the bridge usage. Since online language is often part of the evolution of words, lets look at some history of the word "Troll."
[The usage of the word troll has developed over time. It might have had the original meaning of supernatural or magical with an overlay of malignant and perilous. Another likely suggestion is that it means "someone who behaves violently"] - wikipedia.
At the bottom of that article are links to related materiel, including the wikipedia artile on "Troll (Internet)" which defines a Troll as:
[An Internet troll, or simply troll in Internet slang, is someone who posts controversial, inflammatory, irrelevant or off-topic messages in an online community, such as an online discussion forum or chat room, with the intention of provoking other users into an emotional response or to generally disrupt normal on-topic discussion]
I believe it is the presentation of those opposing viewpoints that you mention that is the reason they are being labelled "trolls".
Here is more from the "trolls (Internet): wikipedia article:
[Prior to DejaNews's archiving of Usenet, accounts of trolling were sketchy, there being little evidence to sort through. After that time, however, the huge archives were available for researchers. The most likely derivation of the word troll can be found in the phrase "trolling for newbies," popularized in the early 1990s in the Usenet group, alt.folklore.urban (AFU). Commonly, what is meant is a relatively gentle inside joke by veteran users, presenting questions or topics that had been so overdone that only a new user would respond to them earnestly. For example, a veteran of the group might make a post on the common misconception that glass flows over time. Long-time readers would both recognize the poster's name and know that the topic had been done to death already, but new subscribers to the group would not realise, and would thus respond. These types of trolls served as a Shibboleth to identify group insiders. This definition of trolling, considerably narrower than the modern understanding of the term, was considered a positive contribution.]
[By the late 1990s, alt.folklore.urban had such heavy traffic and participation that trolling of this sort was frowned upon. Others expanded the term to include the practice of playing a seriously misinformed or deluded user, even in newsgroups where one was not a regular; these were often attempts at humor rather than provocation. In such contexts, the noun troll usually referred to an act of trolling, rather than to the author.]
[Application of the term troll is highly subjective. Some readers may characterize a post as trolling, while others may regard the same post as a legitimate contribution to the discussion, even if controversial. The term is often used to discredit an opposing position, or its proponent, by argument fallacy ad hominem.]
[Often, calling someone a troll makes assumptions about a writer's motives. Regardless of the circumstances, controversial posts may attract a particularly strong response from those unfamiliar with the robust dialogue found in some online, rather than physical, communities. Experienced participants in online forums know that the most effective way to discourage a troll is usually to ignore him or her, because responding tends to encourage trolls to continue disruptive posts — hence the often-seen warning: "Please do not feed the trolls".]
[Frequently, someone who has been labelled a troll by a group may seek to redeem their reputation by discrediting their opponents, for example by claiming that other members of the group are closed-minded, conspirators, or trolls themselves.]
I hope this helps. You may want to read the full wikipedia article for even more.
EN