The money question is...what can we do as webmasters to beat this spam technique in the current google testing environment. Hard to surface sites in a sea of similar contents. Unique or not.
Multi domain spam when coupled with burn and churn technique can be quite powerful.
I don't think it even has to be sites hosted by the same person or company. 10 competitors running against each other all with similar content can result in this phenomenon too? as with against the completed automated scrapers.