Why is it that a party would keep obviously tainted people around? Both parties have done it, mostly when they are in power. My thoughts on this below...
So you are the chair of the Defense Apropriations sub-committee. Your bribary shopping list is a standing joke among staff, representatives and lobbyists. Why would anyone want you to stick around? Or, you are a 16 year old page being preyed upon by a senior member of congress, what advantage is there to letting the predation continue?
Try this: If everyone knows that you are taking bribes that are not part of the standard K-street deal, you are pwned. You will do what you are told to avoid being exposed. Now take this idea, and apply it to a young page who wants to be a player in government when (s)he grows up. Your contacts with Foley get you noticed around the halls of power, you get more notice as you move up through the machine. When you get to the point that you think you are a player, you find that you were bought and paid for long ago.
I'm sure that there are many other ways for these people to "make their bones". And that is how I look at it, do something for the family that makes you owe them your safety, job, power, image, and they have you for life. I hope that I'm just paranoid about these things, but I started thinking about this when "Duke" was exposed. He was my congressman, and I couldn't figure why everone knew he was a felony bribe-taker, but nothing was done. I assume that skeletons are held by both parties, but the threat of exposure only works if you use it sometimes. I guess that my point is that the predatory abuse of children should have risen to that level immediatly for anyone that heard of this.