Trolls used to be members of the newsgroup they trolled, just with a
habit of only making posts which stirred things up.

Now the alt.troll players are coming in with an agenda. The usual tactics
involve sitting in a "home" newsgroup (usually one already "owned"). They
target groups which they sometimes justify as "full of people who are too
involved with something and need to be forced to quit and rejoin the real
world". Crossposting to many newsgroups at once which they feel they can
convert to garbage. The "scoreboard" goal is to get the traffic in a
group up over 75% worthless trash so that anyone coming into the group to
ask a real question will be turned off by what they see.

Filters and killfiles do not affect alt.troll players. In fact, they aid
them. The regulars fail to see what the newsgroup really looks like and
the group fades from use without them understanding why.

You CAN hurt them if you discover their "home" newsgroup where they sit
and watch all of their handywork. Deleting that group from all
discussions, or even trimming the crossposts to only the group you are
in, can help. Some groups are heavily trafficked by only a couple of
trolls because troll in home-group A is including group B in his posts,
and troll in home-group C is also including B, so they end up troll-
responding to each other building a traffic count in the other groups
which both include in their posts.

It can  also be helpful to forward the posts with full headers back to
the posting source. Such actions are usually agains the guidelines of the
source system.

Gandalf  Parker