Fake opinions are perhaps the most insidious spam and they're growing in Australia.

If you spend your time reading forums and blog comments you've probably noticed the rise in suspicious posts designed to defend certain companies and certain points of view. It's been happening for years, but it seems these astroturfing efforts are becoming more organised.

Faceless astroturfing trolls are manipulating online debate.

Keep in mind that I'm not talking about people who genuinely hold strong opinions. They're entitled to express their opinions, whether or not I agree with them. Some of these people are trolls though, in that they enjoy starting arguments, belittling people and acting like jerks. This kind of trolling is the price we begrudgingly pay for the right to free speech.

Astroturfing corporate trolls are a different breed in that they're getting paid to push a certain point of view and create the false impression of a grass roots movement (thus the "astroturfing" tag). In some ways they're the enemy of free speech in that these fake opinions are designed to counteract real opinions or simply drown them out.