Individual politicians desire power, and often take short-cuts to get it. That is a characteristic of politicians, not one that can be attributed to any single political party. What CAN be differentiated between parties is how the party deals with their politician members who are caught taking bribes or selling the services of their offices for personal gain.
Steve Benen points out that the Democrats have found that the Democratic governor of Illinois, Rod Blagojevich, was attempting to sell his appointment to the recently opened Illinois Senate seat, and the Democrats threw him under the bus.
The Republicans have taken a completely different tack with both Alaska Senator Ted Stevens (as guilty of taking bribes as O.J. was guilty of murder) and Minnesota Senator Norm Coleman, currently under investigation for taking vast sums of money under the table to support his lifestyle. The Republican approach is to defend these crooks and keep them in government as long as possible.
I choose the Democratic approach, thank you, though I recognize with regret that particularly at the state level the Democrats unfortunately also protect some of their own crooks.
Local governments are a completely different story, of course.