But give people movtivation and they will find out.
According to this news story, http://www.siliconvalley.com/mld/siliconvalley/news/editorial/15613719.htm, that's what happened in NH. Briefly, a staffer for a Republican Representative in a tight race pretended to be a Democrat to encourage other Democrats to give money to "more winnable" races.
For those of us that follow this sort of thing, it is another aspect of what is sometimes referred to as "information war." Information war is distinct from the civic engagement the internet enables; in fact, it is designed to cripple that effectiveness. It takes the form of trying to artificially generate an appearance of support for your position where none exists, or disrupt the efforts of an opposing perspective to present its view or discuss things internally effectively.
But the same technologies that permit disruption also permit ways to route around the damage. It is a constant tug-of-war between the positive aspects of civic engagement the internet enables, and the negative aspects of enabling information war.
Ultimately, however, the determining factors on the internet and its usefulness as a tool for civic engagement and research is trust. Over time, some sources are recognized as trustworthy. You can blow this trust -- as happens when bloggers get paid under the table to support or oppose certain perspectives or views. But many people recognize that trust is far more important than a quick buck. Not necessarily for any moral reason, but because a blog stands or falls on whether readers continue to read it.
Unlike the mass media, where viewers have limited choices and a network or newspaper makes or breaks someone by chosing to provide a platform, anyone can read anything on the internet. We have friends or relatives that offer different perspectives and forward different articles or links than what we might find ourselves. We read and value them because they have something about them that makes us trust them -- whether it is the reasonableness of the argument or the endorsement of someone whose opinion we value.
Which is why I continue to believe that civic engagement wins out over infromation war. But I'm really just a gray and white cat with opposable thumbs, so what would I know?