I believe the women. They gain nothing by lying. In fact, it's probably quite embarrassing to admit that Bill Cosby raped you. These women have jobs and reputations. I don't think they would put those things at risk to lie about Bill Cosby raping them.
A woman that spends several days in Cosby's company, has sex with him, sees him again a few years later, then spends a couple of weeks with him again, and having sex again, has credibility problems, IMO, when she later claims that that first encounter was rape.
And sometimes a few women are willing to risk their careers and even jail time over anger at being rejected and lied to, or even just to get their kicks.
Here is a case of such from Australia, the infamous 30 Second Rape
"Perth resident Kevin Ibbs was having consensual sex with Christine Watson on the night of 29 November 1986. Watson, a close friend of Ibbs's wife, Katrina Carter, was living in the same house with Ibbs and Carter. The sex act was taking place with the full knowledge of Carter who was in the house at the time.
As Ibbs was nearing ejaculation, Watson suddenly withdrew her consent to sex (so she later claimed) and tried to push Ibbs away. He continued for a short time. Too late, he was trapped.
He was charged with sexual assault and found guilty under the new law. The judge found that Ibbs had continued sexual intercourse for about
thirty seconds without consent (for which he was later dubbed the 30-second rapist).
Judge Geoffrey Kennedy (pictured) sentenced him to
four years imprisonment. [Details of the judgement and appeal]
Some years later Watson admitted to police that the whole incident was a set-up orchestrated by Carter to have Ibbs charged with sexual assault to get him out of the house they were sharing."
Feminism in Australia - the diabolical episode of the 30-second rapist
Wow, lie about a rape all to get a guy she didn't like out of the house that they shared and risked jail.
That make sense to anyone?
So, no, I don't think the women have automatic credibility just because they say it happened.