If your job is to make sure that ducks do not get any of the free food, does it not make sense to take a closer look at anything with features such as webbed feet, feathers, or a large bill to see whether it quacks?
Skip to the bottom of the (bland) GovExec article below about the IRS response to a Question about the 501(c)4 exemption situation to a link that goes to a PDF list of the nearly 200 organizations that were given approval for the exemption -- and ask yourself which ones jump out as worthy of additional scrutiny for possible political activity using simple common sense. While there are some groups with names suggesting a progressive agenda, rightward-seeming names predominate. (My apologies for not being able to provide a direct link to the list, but it is definitely worth the effort to take a look.)
The facts are not as sexy as calling out the IRS for political bias. It is fair to question whether some of the approved groups (left or right) are really entitled to the exemption and call for greater scrutiny of their activities.
http://www.govexec.com/...