It's because she's a 'Rat, and no one in the 'Rat party cares about that kind of stuff. Republicans, on the other hand, have the more conscientious folks who care about family values, and Newt would go over with them like a wet dish rag. It's a real difference in philosophies and ideologies, and the fact is that our candidates have to live to higher standards than the 'Rats to get elected.
I guess it all depends on what you think of when you think of Hillary's baggage.
I think of Whitewater and a bunch of unexplained suicides surrounding her and Bill. I think of her casually mentioning that Bill is a "hard dog to keep on the porch" when asked about his philandering. Do even Dims really want a woman running the country that is that dismissive ? If she has such disdain for marriage, isn't she dissing half her base ?
A lot of Dims were willing to let Bill's sexual antics slide because he was POTUS, but that doesn't mean they weren't embarrassed just the same. Do they really want him back in the limelight as First Husband ?
I think she's got her own baggage plus Bill's baggage, and that would be too much. She'll alienate some Dims and Bill will alienate others. Together she stands no chance.