Darren points to an article on The Register, which is an interview with a link spammer.

Of particular interest is how link spamming originated:

“It was around December 2003: Google did what was called the ‘Florida update’. It changed the algorithm that measured how high a site should be ranked to spot ‘nepotistic’ links and devalue them. So if you had a link farm of sites with different names which linked heavily to each other, they were pushed down,” explains Sam.

So the link spammers – who prefer to call themselves “search engine optimisers”, but get upset when search engines do optimise themselves – turned to other free outlets which Google already regarded highly, because their content changes so often: blogs. And especially blogs’ comments, where trusting bloggers expected people to put nice agreeable remarks about what they’d written, rather than links to PPC sites. Ah well. Nothing personal.

The reality, as I’ve always suspected, is that it isn’t just about SEO. The ultimate goal is to get people to click through. For every click, the link spammer gets money. Sometimes as much as 1$ per click. And when he can send out 1-2 million blog comment spams in a night, he needs very little in terms of click-through to make a profit. A very, very large profit.

One link spammer I know (okay, he’s the only one who’ll admit to it) makes roughly 30K per month from link spamming. My challenge to him? Start a blog ;-)