Event: Drama in Michigan

What do we make of this:

Michigan Messenger: Lose Your House, Lose Your Vote.

Or this:

Michigan Messenger: Michiganders see red about voters’ rights threat

And this:

Detroit Free-Press: GOP Won't Use Foreclosure List to Block Voters.

? ? ?

Now everything that the Republican Party does doesn't have to be evil and sinister. However, it is clear that someone isn't being on the up-and-up here. What I am very curious to know is, on what grounds do challengers confront voters, and what incentives prevent them from making frivolous charges?