A solar company is under investigation currently for posting five-star "reviews" on a website productreview.com.au with the ACCC. This is not the first time an organisation has been charged with doing this. There is an interesting discussion on the whirlpool forum about it, which is worth reading if you have a website, or you are thinking of doing this and I suggest you read the ACCC guidelines here.
We had something similar happen to us here. Readers may recall a character Jack and Nelson, who kept writing negative reviews on our posts and discussions. It turned out to be a person in a competitor company of ours.
He got caught because he was stupid, as he accidentally posted under a name that stood out, then he was ignorant as clearly, he did not realise that almost all browsers have a trackable and unique fingerprint and because he was careless and exposed his IP address. One point led to another and another, and he was caught. Once notified and told what a ~@!#@ he was for doing this. He stopped immediately, maybe we should have gone to the ACCC too?
At the time, I was I confess hurt and just happy he stopped.