BBC's Panorama will tonight (11 February) focus on the dark side of social media influencers. It is unlikely to make happy viewing.

There can be little doubt that the stars of Youtube, Instagram etc. carry great weight and, well, influence. And with that responsibility.

But where does that responsibility rest? 

Of course, individual Youtubers wishing to protect revenue streams will want to be careful about the brands they associate with.  But can they be trusted to do and say the right thing?  Experience suggests not. 

The social media channels?  Well, they don't seem to care.

Ultimately, responsibility must rest with the brands themselves.  

And therein lies the rub. In the Wild West rush to bag an influencer, are brands leaving themselves exposed to a PR nightmare?  Panorama thinks so.