The traditional definition of a troll refers to a member of a community or usenet group who makes posts deliberately designed to attract responses of outrage or indignation. It is the troll's intent to "hook" unsuspecting members into responding, (hence the term "trolling"), thus providing him/her self with the satisfaction of knowing they have impact on others.
A distinction must be made between true trolls, newbies who are undergoing growing pains as they attempt to adjust to community standards, and regular community members who simply have strong but otherwise harmless, dissenting opinions. Trolls should be removed, newcomers assisted, and contributing community members given at least a modicum of respectful distance.