I don't think you have to assume good faith at all in these situations. If someone comes up with a correlation of X statistic with Y statistic in a fashion see

I don't think you have to assume good faith at all in these situations. If someone comes up with a correlation of X statistic with Y statistic in a fashion seemingly coming from nowhere, they either say why they started studying the correlation or show the correlation is incredibly strong. I think that's pretty much what "extraordinary claims require extraordinary evidence" winds-up meaning.