This comes in a year when some PR consultancies have already been hauled across the coals for a tendency to employ large numbers of unpaid interns and others (sometimes the same ones) have been slammed for advising dodgy foreign regimes.
It didn't help that B-M had already faced allegations over dubious ethics, thanks to it having worked for such clients as Philip Morris and Union Carbide on controversial campaigns in the past.
But while B-M should indeed be castigated for the Facebook briefings - the agency has since apologised and said this was not typical behaviour - in-house communicators should also be taking their share of the flak.
B-M's transgression took place in the US and Facebook's UK consultancy, Blue Rubicon, was quick to distance itself. But this itself suggests a less than 'joined-up' global comms approach.
Indeed, Facebook reportedly hired B-M specifically for this anti-Google campaign, meaning the in-house team was, at very best, naive.
In this age of openness and interconnection - from which Facebook has benefited to the sum of billions of dollars - it was crazy to believe that such activity would remain below the radar. After all, emails to an online journalist are hardly untraceable.
And we should remember this is Facebook; a new type of firm supposedly built on young, forward-thinking west coast American principles.
Above all it reminds us acutely of the new comms paradigm.
It has always been tempting to brief against one's rivals - and to many 'all is fair in love, war and marcoms'. However, this must now be viewed in the light of public life that is almost transparent today.
If the MPs' expenses scandal, Wikileaks and the recent furore over super injunctions have taught us anything, it is that the truth will out. PR consultants must realise this if they are to give astute and valued advice. But client organisations should urgently adjust their commercial and public affairs strategies accordingly.