This isn't really a surprise. It was really dumb of Cain to keep pushing once the women started coming out.
I can think of at least one guy who kept pushing after a series of bimbo eruptions and did quite well in a couple of elections:
... Cain's gaffes and inexperience, especially about foreign policy, are the real problem with him, not a series of allegations about his personal life.
What your forgetting or leaving out is that Clinton only had Jennifer Flowers claiming they had an affair while he was in the primaries. Cain hasn't even gotten to a primary yet and we've already have a handful.
As for Cain's other problems, after W I wouldn't bet on any of that actually stopping him.
There were several allegations that Bill Clinton had other affairs, while he was still campaigning. But since no one else came forward to show themselves as Gennifer Flowers did, the (liberal) media treated them as if they did not exist. ...
The problem for Cain is that he has had several "Gennifer Flowers" come forward. Where has the media treated him differently? In fact I wasn't aware of his mistress till she came forward but it seems that at least some of the press was aware of it. Cain's mistress didn't become news till she came forward though.