It's extremely difficult to keep your hands clean if you're politically involved, damned near impossible if you hold office. The reason is the existence of conflicting responsibilities.
If you hold office, assuming you are ethical, there are two things you want/need to do:
1. Vote your conscience
2. Help people
Let's say you're elected to Congress. You don't want to be responsible for Business As Usual. You want to take care of your constituents, keep your commitments and be proud of every vote you cast.
You speak to a fellow Congressman who makes you an offer: You scratch his back, he'll scratch yours. You want support on a gay rights bill, in part because one of your children is gay, and this Congressman wants support on a bill to ease environmental standards on a company in his district. You're a pretty ardent envirnomentalist and you were supported during your last campaign by environmental organizations, but you're really, really anxious to see this gay rights bill passed.
If you follow this guy, the gay rights bill passes; if you don't, it probably doesn't. The environmental modification for his district will probably pass either way though, if it doesn't and you voted against it, you've made a powerful enemy.
If you back this guy, you have to explain to environmental organizations in your district why you voted against them, in spite of their campaign support and, even worse, in spite of your convictions. You end up looking like a typical politician.
If you don't back this guy, you have to explain to your kid why the gay rights bill didn't pass, and you may have to explain the same thing to gay rights organizations that supported your campaign. You will end up preserving an aspect of your personal reputation but you will not accomplish anything in terms of policy. You will have been helped in a sense by maintaining a reputation for issue integrity, but you will not have helped anyone else.
What do you do?
Which decision is right? Which decision is moral? The dirtier decision is the one that helps people and helps you accomplish more later because you generate polical capital, you now have a reputation on the Hill as someone you can work with, and you have the favorable attention of someone important. The higher you rise, in terms of things like committee assignments, the more people you can help.
The cleaner decision enhances your reputation for integrity. To what extent is that critical and to what extent is it self-indulgent? Why are you here? I hope it's not to enhance your reputation.
A lot of you would ask more questions; I know I would. How bad environmental damage are we talking here? Do I have the option of abstaining on a vote and, if so, how much would abstaining help me politically, either with my constituents or with my powerful colleague?
So much weaseling, right at the beginning of your Congressional career, and yet is the weaseling more moral than self-indulgence is because weaseling produces, from a legistlative standpoint, a better result for your constituents, along with the potential for more results down the road? The argument can be made both ways.
If you opt to vote your conscience issue by issue, you presumably do so to keep your hands clean. However, you failed to help your constituents when you could have, easily, so are they really clean? That's debateable.
Is the Slippery Slope a factor? If you compromise once, are you obligated to compromise the same way all the time? Will your priority become your re-election more than your constituents' interest on the grounds that you have to stay on the Hill to do them any good? I've read Hentry Adams. It happens. You could end up as a full-time weasel who doesn't really help people, except by accident.
I'm not telling you which way to act. I'm not telling you which way I'd act. I'm just telling you that this is a very typical political dilemma. You can't navigate the territory while keeping your hands clean if you want to do the job effectively that you were sent to do. You have to figure out how to walk a tightrope, how to decide when compromise is too much to stomach and when it isn't.
You're not in Congress. You're a voter. An election is coming, and you have an enormous advantage over Congressmen:
You vote with a secret ballot.
You can steer a result without it affecting your reputation and without showing visible support to anyone you view as reprehensible. You may be able to have your cake and eat it. You may, for example, be thoroughly pissed at the President and, as a result, you don't want to show him support, but you understand the difference between a Supreme Court nominee put forward by Obama or Romney, so you can minimize the damage without visible political consequences. Or you can conclude that the compromise is too awful to stomach and that the Supreme Court consequences are worth withholding support over.
The point is that all your choices have consequences and that you bear responsibility for those consequences. If you're involved in politics, you're intrinsically playing in dirt, so don't expect clean hands. You won't get them.
Just choose your dirt wisely.