Earlier quoted context omitted.
All the BBC podcasts are ad-free, but I get them from within the UK. I am not sure if they have ads if served in other countries.
Hmm, at what point do all the trailers for other shows tip in to the advert category? I wouldn't want to try counting how many times I heard a trailer about 13 Minutes to the Moon last year, which I'm picking on specifically because I actually enjoyed it to make the point that the bucket choice can be very subjective.
I'd say at the point where people would get upset if they were paying money for an explicitly ad-free podcast.