When adding a podcast by URL, that URL appears to be added to the podcast directory for everyone to discover. But not all RSS feeds are meant to be shared with the world. (E.g., private feeds such as those made by Justcast.) With that in mind, I would like to request a flag when subscribing to a podcast by URL, to ensure that the subscribed feed is not shared with the world.
@JRobelen When you add a podcast via URL it is added only for your account. It will then show up in searches that you make as your user. It will not show up for other users unless they themselves add the same private feed via URL. 
Thanks for that reassurance. I saw that I could continue to find the feed in a search even after I deleted it from My Podcasts and that worried me. I was afraid that adding an unknown podcast would be considered a “suggestion” for the public list of podcasts.
If not through user suggestions, how are you getting the complete list of podcasts for Plex’s searchable podcast directory?