One little noticed part of the corruption problems encompassing Democrats like Rod Blagojevich in Illinois and William Jefferson in Louisiana is that they come from the more conservative/DLC/New Democratic wing of the party. Blago, when he was in the House, was the only Illinois Democrat to vote for the war, and as Governor pursued culture war issues like cracking down on violent video games. Jefferson was one of the few CBC members to vote for the war in Iraq, and has a well-trod history of voting against corporate regulations.
New Democrats are kind of struggling to find their niche at this point, ideologically speaking. There's not a lot of oomph left in the free market Democrat mantra, and the corruption scandals here suggest that this is in some ways simply about low rent pay to play.