Trump found dozens of women who were willing to accuse Bill Clinton of rape and brought them over to some of the debates with Hillary.
It was three women (along with a fourth who was apparently mad at Hillary for representing her rapist in court), and all of them had publicly accused Clinton back in the nineties.
There's a reason we don't rely on personal incredulity when it comes to such serious accusations.
Who says we don't? I think if the alternative is incredible enough - such as a large number of women all falsely accusing Trump, and only Trump, as if he's the only controversial businessman/politician in the world, of sexual misconduct - then personal incredulity is a perfectly valid reason to make a judgment about, yes, even serious accusations. I wouldn't support that in any kind of legal context, because we don't put people on trial for having poor character or probably having committed a non-specific crime in the past. Fortunately, we aren't talking about that.
You may find it unlikely that so many women would be bought/convinced to put forward a false accusation, but I find it unlikely that so many women kept quiet until the very moment Trump was about to become a hell of a lot more popular and powerful. That they would all simultaneously, unprompted, choose the very worst moment for them to speak up... that defies all logic. They deliberately waited for the time they were least likely to succeed, to get justice, because... reasons?
This doesn't make the case for the women being dishonest or otherwise unreliable. The premise of it being so illogical to make these accusations of Trump at that particular point of time is unchanged regardless of whether or not the women were telling the truth. Either way, Trump was about to become far more powerful and popular. Either way, their accusations were extremely unlikely to succeed in bringing him down.
Nevertheless, the reasons for why they came forward when they did (presumably you're referring to October 2016, when the bulk of them were reported on) are pretty straightforward. Trump was at his highest profile, his behavior towards women had recently come under scrutiny with a NYT piece on the subject and the
Access Hollywood tape, and Trump had flatly denied ever sexually assaulting women on national television. A number of his accusers have cited that as the moment they decided to speak up:
https://www.nytimes.com/2016/10/13/us/politics/donald-trump-women.htmlhttps://people.com/politics/donald-trump-attacked-people-writer/https://www.palmbeachpost.com/news/national-govt--politics/palm-beach-post-exclusive-local-woman-says-trump-groped-her/aLcLWjmxbmudQMc7TXuxiK/That's really not suspicious. It's entirely understandable.