Unethical Interviewer Behavior

Is there a place where tech folks can warn each other about unethical interviewer behavior? I'm talking about behaviors such as:

--asking for extensive free work during an interview

--"take home tests" which are critical to the interviewer's startup, and are unpaid

--asking the interviewee to divulge sensitive information such as trading strategies or other nonpublic materials

--interviewing employees of a competitor to gather information when there is no real job opening

--and other unethical interview behavior

As an experienced data scientist, I personally have encountered all of these that I've listed, and I would guess that other hn readers have experienced something similar. It would be great if we could share such experiences so that others don't waste their time on such interviews.