There are several debating techniques which detract from the truth instead of illuminating it, and two of the most pernicious involve straw men and false equivalency.
The use of straw men involves finding the most despicable person on the other side of an issue, setting him or her up as an authority and then knocking him down. Fox News uses straw men all the time. They bolster Al Sharpton as the point person on racial bigotry and then use his actions on Tawana Brawley and other questionable statements to denigrate the entire movement.
MSNBC uses Rush Limbaugh in a similar way, except for the fact that unlike Al Sharpton, Limbaugh has real power. And this brings us to the second technique, known as false equivalency.