Don't count on it. There are many software developers out there with knowledge of NLP algorithms, statistics, symbolic systems, etc. who aren't employed by Googles, Facebooks, Ciscos and Twitters. They're bored out of their minds and waiting for a challenge.<p>As time progresses, SEO companies will adapt. I contributed hundreds of thousands of pages of web spam prior to the Panda modifications. If I were still working at the company I did it for, and there were proper incentive, I would definitely be able to get around Panda.<p>It took me about 10 hours to build a cute little tool, and after about 3 months of using it judiciously, we were able to push many sites up to number one for some very competitive terms. The search engines might be ahead now, but there are thousands of intelligent programmers out there trying to pick the black box apart. No black box stands unbroken forever.
The companies who hired the shady SEO companies to spam the internet presumably paid them; I wonder how they'd feel about paying content hosts to remove those comments as well.
It seems like there's also an inverse application - if you have a competitor, post a bunch of spammy blog comments for them and watch as how google penalizes them.