Wikis will tend to have some kind of WikiMission to provide some guidance as to what topics are appropriate. Usually there's some tolerance since it keeps things relaxed and usually the Wikizens will lose interest and things balance out. Every so often there is an OverwhelmingTopic that although may be within the WikiMission, severely skews the WikiMind?.
Consequences: I suspect that the main consequence is that people leave, perhaps never to return. The only other consequence observed was a minor WikiMindWipe. This is probably related to not being able to respond or defend comments made on previous writings.
Treatments: WikiEmigration seems to be the only treatment. Technically Wiki:ExtremeProgramming didn't move to another wiki but the mailing list and newsgroup seem to have served the same purpose.