American investigative journalist Sharyl Attkisson, author of Stonewalled, offers a look at astroturf—the way false climates of opinion can be built up, principally through new media.
Yes, just as new media can enable voices that have never been heard before to finally be heard, they can also enable pressure groups and lobbies to create the impression of a broad consensus, which they hope will result in changes to legislation, regulations, or funding that will benefit them:

Astroturfers often disguise themselves and publish blogs, write letters to the editor, produce ads, start non-profits, establish Facebook and Twitter accounts, edit Wikipedia pages or simply post comments online to try to fool you into thinking an independent or grassroots movement is speaking. They use their partners in blogs and in the news media in an attempt to lend an air of legitimacy or impartiality to their efforts.

Astroturf’s biggest accomplishment is when it crosses over into semi-trusted news organizations that unquestioningly cite or copy it.

It works because the Internet is not a physical neighbourhood. Most users can’t just poll their neighbours to determine a consensus. So when we hear that children must be sexualized in kindergarten to prevent rampant child sexual abuse, we may have no means of determining fact amid the howls for action now! from Astroturf City.
Moreover, if all local media have been astroturfed, we may not know, for example, that in one case of a bold new sex ed curriculum, a deputy education minister who claimed credit for it, recently pleaded guilty to child porn charges —until it is too late. By the time the truth is safe to discuss, government is firmly in the hands of the astroturf units, as they had intended. It’s the timing that is the key.
Which makes Attkisson’s discussion critical for those of us who, pressed for time, must spot those fuzzy green fakes early:

The language of astroturfers and propagandists includes trademark inflammatory terms such as: anti, nutty, quack, crank, pseudo-science, debunking, conspiracy theory, deniers and junk science. Sometimes astroturfers claim to “debunk myths” that aren’t myths at all. They declare debates over that aren’t over. They claim that “everybody agrees” when everyone doesn’t agree. They aim to make you think you’re an outlier when you’re not.

Astroturfers and propagandists tend to attack and controversialize the news organizations, personalities and people surrounding an issue rather than sticking to the facts. They try to censor and silence topics and speakers rather than engage them. And most of all, they reserve all their expressed skepticism for those who expose wrongdoing rather than the wrongdoers. In other words, instead of questioning authority, they question those who question authority.

Make no mistake, if you discover wrongdoing in education, you may be the target of attack because you once quit high school to start a successful business. If you discover wrongdoing in a social welfare agency, you may be accused of “bigotry” against the ethnicity of the person whose actions you are reporting. If you report abuse at a public old folks’ home, much may be made of the fact that you are not a physician. (But if you are a physician, your competence or mental health may be questioned.)
‘Twas ever thus, you say? No, ‘twasn’t ever thus.
New media ramp it all up by stripping the accusations of face to face interaction and traditional time lapses. When all accusations had to be made in person or by slower methods, it was much easier to identify, roll up, and stow the astroturf somewhere. New media’s speed benefits the ‘turfers greatly.
Here is one of Attkisson’ pointers for detection:

A close third is an array of blogs that use words such as “science” and “skeptic” in their titles or propaganda in an attempt to portray an image of neutrality and logic when they are often fighting established science and serving pro-pharmaceutical industry agendas.

In this short vid, Attkisson tells us some very interesting things about Wikipedia’s astroturf, for example, in case you know someone who is inclined to trust that source:

See also: How Wikipedia can turn fiction into fact (Once enough canards are in circulation, entire fictional scenarios can be created that are difficult to confute because they appear to be well-sourced via constant repetition.) Typical astroturf technique.
“Wikipedia is my library” should be the new definition of sloth. Denyse O’Leary is a Canadian journalist, author, and blogger.