There's a difference between buying links, which Google actively started prohibiting at a certain point, and the automated forum spam you are mentioning. The latter is done using software like XRumer, and has always been penalized by Google. The former wasn't prohibited in the beginning, when link deals were often mutual agreements, most of the time involving a traffic component as well.<p>The snake oil salesmen that are mentioned, are the ones who actively participated in the scheme by selling links and making a buck, and are trying to make another quick buck now that the rules have changed.<p>Moreover, some links aren't even paid at all, but just look manipulative. For example, if you developed a wordpress theme, and your link is in the footer of tons of blogs, you might get penalized for manipulating the anchor text of your links in a non-natural way. In those legitimate situations, webmasters do have a moral obligation to cooperate.<p>I don't think anyone would think that of an honest entrepreneur being spammed to death by link spamming software.<p>On a side note, there are plenty of forums on the web that have survived the spam wave, if it were core to your business, you could have protected yourself.