My thought has always been that trolls either come in three categories. The first are those that feel repressed or afraid to stick up for themselves in the real world and use the online world to let loose the venom that they are unable to release in the real world. The second are those that can't seem to handle the fact that others can post comments that are more original, intelligent, or funny than their posts. Finally, there are those that for some reason would rather not engage intelligent conversation on a site, and just bash whoever seems like the best target at the time. If anyone has any other thoughts on the categories of trolls, please add to the list.