Throughout history it has been one of the methods for creating political momentum and it has a history of disaster.
What happens is that when the population finds that it has been mislead, duped or drawn into something they later regret, they are very angry.
Joseph Goebbels used astroturfing (in a 20the Century form) to create the impression of widespread support for the Nazi party in Germany with considerable success.
I guess that companies and organisations (even political candidates) and campaigners don't really like to be associated with the Nazis when they use this silly, and potentially dangerous approach at persuasion. Bet your life, I will make the comparison.
I hope that Richard Bailey's points are taken to heart by the CIPR. In fact one would expect a comment from the Chairman of the Ethics Committee to make a clear statement sometime in the future.
It may be that the CIPR's Chief Officer is dismissive of social media but the President whose travelogue is of the genre might wish to assist the President Elect representations to the Hansard Society project looking at the role of lobbying organisations in the British political system to have Atroturfing on the agenda.
As for the rest of us, there is a simple rule. Do PR and if you are a member of any of the professional association in the UK, expect to be chucked out on you ear if you use Astroturfing because a lot of us are watching, for the sake of the profession.