Earlier quoted context omitted.
Here's my (completely unsubstantiated) theory. It happend literally the day after crossing $500 & 50K views in adsense. I'm guessing one of those was a trigger for manual review by some contractor, perhaps overseas. They looked at my sites for 3 sec, found them to be cookie-cutter and decided to blacklist the account. I get the impression they shoot first, ask questions later. I didn't feel like dealing with it all o…
I talked to someone from Google at I/O who should know and he claimed they don't play "Whack a mole" with websites. They will tweak their ranking algorithm to punish the behavior they see in a web site they don't want to be ranked.
For example, one of the big issues in blackhat spam this past year was illegally hacked sites. Our algorithms weren't doing the best job on hacked sites, so the manual team kept an eye out for hacked sites to remove them (and often to alert the website owners that they'd been hacked). The data generated by the manual team helped us build and deploy multiple new algorithms to detect hacked sites, leading to a 90% reduction in the number of hacked sites showing up in Google's search results in the past few months. That decrease in hacked spam in turn frees up the manual team to tackle the next bleeding-edge technique the spammers use.
I suspect every major search engine uses similar approaches: try to stop the majority of spam with algorithms, but be willing to take action in the mean time while engineers work to improve the algorithms.
