Would somebody like to provide concrete, researched evidence on sites that have been deindexed/punished purely because someone bought a few links to them, or posted others in an undesirable spot. We could all be rich in a month, how much would a multi-national pay to take down a rival.

There are a few people in this world who do sell negative services but they don't approach their task in that way. More a long, concerted campaign, that still often fails, not least with search engines.

Take the two "banned" sites mentioned in this post. Sorry poppo but these aren't websites, just doorway pages, full of duplicate text. Why would anyone want them in their index.

An obvious example but there's normally a reason. Of the hundreds of sites I've seen that have screamed foul play, I can think of one that was genuine. That was a concerted campaign, registering linked overseas domains, bribing insiders, etc.

For most people reading this thread, I would take a look closer to home.