Why do trolls bother? After all, they have to come across the blog entry, whether on Google or through the fatosphere feed (which denotes a whole 'nother level of unhealthy stalking behaviour) read through an entry (theoretically) and then actually take the time to come up with a reply, type it out, go through the "hidden pictures" anti-spam rigmarole.....for what? Are they so pantingly desperate for a chance to be nasty?
Durkheim and the buzzword "morality" aside, a society develops rules of conduct (written or unwritten) which allows it to function. You'll see that in a close-knit society people are much less likely to be rude and/or violent towards each other (not that its impossible, especially in familial abuse). This is because there are clear repercussions which make the individual responsible for their actions. Misbehavior is more likely to reflect on them throughout their lives.
As our "society" expands to a larger community where you cannot possibly know everyone, you become less accountable for your behaviour. After all, the odds of you ever meeting that person you were rude to again are slim. You won't be reminded of your rude behavior or face social consequences such as ostracization.
As the internet expands our society to a global scale we find that both the chance of face to face accountability is reduced to almost nothing. The dehumanization of text-only communication reduces empathy and the wide mixture of cultures with different rules of conduct confuses the matter further. The mature, responsible person is able to adjust their interpersonal rules of conduct and apply them online as if they were face to face.
It's interesting. Most trolls, by their behavior, would fit many of the signs of a sociopathic personality if they were acting as they do to people outside the internet. Eliminating body language doesn't mean that behavior automatically goes from crazy to rude.
We can also gain insight into those who leave hate-comments by studying the Psychology of Hate. I do think that the profile and psychology of irrational haters is comparable regardless of the target. (NOT making a value judgment or comparison between fat-hate and racism!). Haters, and trolls, are unsure of their social identity. When social identity is threatened people often cling to irrational belief, willing to defend it violently rather than adapt to the new social reality.
Hate can simply be an immature device to achieve detachment. When a troll posts a nasty comment about my weight, they are simply trying to say "I don't want to identify with you" (without, of course, using their words like a grownup). If they really examined their motivations, they'd find that they don't have to be anything like me (and probably aren't.) They don't have to somehow violently separate themselves from me in order to avoid the social stigma they fear. They don't have to post a comment to convince themselves they're not just separated from me by the narrowest margin of social whim.
Or maybe they do, because they fear it might be so.