>And then when anyone points this out, they're accused of poisoning the debate :)

Because they do.

If you're wrong, you're doing their work for them by sowing discord and mistrust in the community. If you're right, you're doing their work for them by distracting from the subject and making the thread about the threat of the enemy within. The one thing you probably won't accomplish is getting them to stop.

The only way to win the game is not to play by their rules, and to not make it personal. If you really believe someone is a shill, report it to the admins, they claim to take this sort of thing seriously.