The climate denier scenario is interesting but the imbalance can be addressed if it's made clear at the outset that the people present represent a certain percentage of workers, and certainly in terms of the BBC this often doesn't happen. How the time is divided between guests might work but doesn't ever really happen, as would mentioning their qualifications. It's then up to the host to ensure fairness of representation, a difficult task for sure.

Great link Bill (not sure I understand it all, will need to read more thoroughly!), great thread.