Yeah and I feel the bots or human assisted bots are getting more and more sophisticated. Even here on hacker news it feels like there is something less organic than before about posts and comments rankings.
It may be that I am getting old and that the culture has changed but I'm not sure...
If I was to setup such a service I would have a simple text bot scanning popular sites for occurrences of my brand name and when a hit occurs it would make an Amazon Mechanical Turk ticket so that workers in Nepal could log a system that cycles accounts to that service so that they can leave a good review to counter the bad one. 10 cents a "counter" review. Why spend a bunch of money for in-organic robo-reviews when you can have real people writing reviews for dirt cheap.
A second service would be to have Americans pressure a site to have detrimental user content removed. For example, if someone starts a thread about how the name of my product was stolen from an indigenous community's recipe, our service would nip that in the bud.
Your brand management department would love us. These services already exist.
It may be that I am getting old and that the culture has changed but I'm not sure...