(1) generic (e.g. swerves the thread toward larger/general topic rather than something more specific);
(2) flamey (e.g. provocative on a divisive issue); and
(3) predictable (e.g. has been hashed so many times already that comments will likely fall in a few already-tiresome hash buckets)
- is the bad kind of offtopicness: the kind that brings little new information and eventually lots of nastiness. We're trying for the opposite here—lots of information and little nastiness.
The best episodes are ones where the guest drives the interview and has a lot of interesting things to say. Fridman's just useful for attracting interesting domain experts somewhere we can hear them speak for hours on end.
The Jim Keller episodes are excellent IMO, despite Fridman. Guests like Keller and Carmack don't need a good interviewer for it to be a worthwhile listen.