> Every podcaster is going to claim that no, it's really what they think, what a marvelous coincidence. It's amazing what someone will "think" when their paycheque relies upon it.
I think there's a lot of truth to this, but there are also plenty of podcasters who will literally try all the products themselves (or have some staff do so) and if the thing is no good, pick a different sponsor. The biggest shows are often in a position to do this without any real sacrifice, other than the time investment in testing: they have loads of sponsors knocking at their door that are all offering similar (large) amounts of money, so they're free to pick the one they honestly like.
Here, I feel like the gray area is that they're unlikely to have tried the alternatives to the product. So they'll give a ringing endorsement of Squarespace or Mailchimp or Purple mattresses, but all that shows is that it's probably decent stuff, not the actual highest-quality or best-price option for the listener.
Overall, though, I feel like it's practically a miracle that we have an online media industry that is free of the totally maxed-out creepiness of website advertising (tracking across media, profiling down to the individual level, etc.) And it's even making money. Just listen with a healthy skepticism about the ads. I think most people do.