I consider myself a "social liberal" because I see governmental enforcement of traditional views on marriage, gender roles & race relations as an assault on personal liberty.
But to the question at hand:
I think Bill Clinton is a good example of the moderate side of liberal ideology. Is it hypocritical for him to say that the gov't shouldn't enforce traditional gender roles and then sleep with his intern? Maybe. But the less self righteous you are about your ideology, the more tolerance folks have for hypocrisy.
Compare Barbara Striesand's opinions on water waste to Rush Limbaugh's on drug abuse. Babs wasn't out there saying that anyone who wastes water should be shown no mercy. She was out there saying people ought to act in an environmentally concious way and adovating reproach or fines for those who don't.
Then -- bam! -- Babs gets caught wasting water. And the enviro liberals do what they always do, and say, tsk tsk, Babs, hit her with some reproach and, if possible, a fine, and we all move on. What's so wrong with that? Should we really be crucifying her for this water waste? I mean, it would be one thing if she was secretly drilling in the Alaskan preserve. But over watering her lawn? I can live with that level of hypocrisy.
Similarly, if Rush Limbaugh was just out there saying he thought drug users should be punished in scale with their crimes, then his oxycotin addiction comes out, no big deal. He gets a fair reproach/fine/punishment and we move on. But he was saying no mercy for drug addicts, right? So the real issue here is not that he says "do what I say, not what I do" (because, at some small point, we all do that) but that he went beyond that and said, "do what I say or there will be no mercy!" Then he gets busted and everyone's glad he finally got his comeuppence.
The more self righteous you are about your ideology, the less tolerance folks have for hypocrisy.