Spammers should be contacted via email immediately and asked to stop. These are the people who present immutable positions. They appear to be initially unwilling to see points of view beyond their own. They push instead of probe. They engage only on their own terms, but may refuse to engage others who utilize the same tactics.
Interaction often escalates and winning is the goal.
They also are keepers of important information that the community may need, but not particularly liked. They ask the tough questions, but may not like to be asked them back in return. Often they won't fully engage or justify their positions. On the other side, they often can help neutralize a polarized situation and offer new, combined viewpoints for a community. They tend to carry new information into a group that has polarized on issues and can be a breath of fresh air.