Because we spend so much time at work and because a bad workplace is such a miserable experience, I think candidates should pay close attention to negative signals, even if they could turn out to be anomalous. Of course, when things go wrong it's certainly important to pay close attention to how that is handled. Basically everything that happens during the interview and recruitment process should be treated as signal even though some of it will be noise.

For employers evaluating a candidate, "if it's not yes it's no" - I would suggest job seekers to have the same attitude. (Unless your current job already sucks.)