If this isn't black-hat, what is? Specifically, an author not disclosing an affiliation or payment, fake accounts promoting it, and fake accounts commenting on those promotions. In the continuum between white and black, what's left on the black side? :-)
SQL injections, vulnerability exploits, or other hijacking mechanisms to inject links directly. In my mind, using a system as designed without breaking any laws lands in grey-hat territory.
Outright spam, like forum and blog comments. Exploiting web sites, or abusing trust relationships (like updates to WordPress plugins or browser extensions) to inject spam into legitimate pages, or to create entire networks of spam pages within unaware sites. Launching deliberately obvious spam campaigns to discredit competing sites.
That's black-hat SEO -- where the behavior itself is probably illegal, even without the intent.
Dont forget SAPE. When I heard of that I knew the SEO world was rougher than I had previously imagined.
For those that don't know, its a Russian run marketplace for link injected/hacked sites. Really big, high quality sites.
I think the point is that those activities are clearly "black hat", while astroturfing isn't inherently illegal. (well, maybe in some jurisdictions it is. I seem to recall that the UK has much stricter "truth in advertising" laws than the US)
It all exists on a spectrum though, and we can disagree on where the line for black hat is drawn, with no one being wrong because it's a matter of opinion.
