to be fair, I've always felt "Believe All Women", despite being a catchy and profound slogan, was a poor one to use because of times when its very obviously not true. I can't think of a better one off the top of my head, but I think it should be more of a "Justice is Blind" connotation , along the line of "Give all women the benefit of the doubt when they make accusations, no matter what their life circumstances might be", and if an initial investigation into it throws up a bunch of red flag like this one has, so be it and skepticism is warranted, but don't ever go into an accusation already assuming there's going to be red flags because a person happens to be a sex worker or homeless or an addict or whatever. It should be more about the initial conditions and attitudes going into an investigation, NOT a view that its a requirement to hold as the investigation goes on no matter how many suspect things are uncovered and pieces don't add up.

This article (I think this is the one) handles the issue in a fairly mature way IMHO: https://qz.com/980766/the-truth-about-false-rape-accusations/

I think its intersting to note that two of the top reasons that false accusers will make up a rape story are (1) Fear of retribution from partner if they knew activity was consensual and (2) Fear of retribution from parents if they knew activity was consensual. Particularly that second one.