I don't want to search out the posts in this thread that I'd like to address so I'll just skim the surface.
First, RAP is a club event and RC recognizes the greater good to the hobby these clubs provide. Along with that RC allows these clubs to use RC to promote the events they hold. That can be a monthly meeting, backyard swap or what's become a mega-event like RAP.
IMO there's no fine line here at all. To me the rules of engagement are pretty clear. SCMAS is a club that I'd assume holds non-profit status and as long as that status remains I see no issues with promotions of their events.
Other events like CFM are for profit and have been handled as such in the past. As regular RC members we can discuss those events with limits based on the posters involvement. So in my case, since I sold at both RAP and CFM you didn't see me participate in those threads in a way that could be interpreted as promoting my offerings.
I think my participation in last years CFM thread probably did more harm than good when the Riff-Raff thing came up. BTW, in retrospect I don't regret any of those comments and still proudly stand by them. In fact I still have the shirt to prove it.
SteveU