What are my options please for hiding specific, admin flagged posts from guests? I'm wanting to be able to "flag" certain posts plugging certain companies as content that should only be viewable to logged in members, and be replaced for guests with a message, for example "This content promotes a non-sponsor and is only viewable to registered members". However this needs to be done per post in a forum and in threads otherwise fully viewable to guests.
Is this getting into the realms of needing a custom plugin?
Could I do it by using a custom BBCode and wrapping the whole post in this? Can you use conditionals in BBCode to censor/replace content?