AlyssaS - 12:33 pm on Feb 7, 2011 (gmt 0)
Hence I would imagine the vast majority of links in these niches are exchanged, paid for or in some way obtained "unnaturally".
They use two evil tools called Scrapebox and Xrumer to create their links (google them to find out the true horror).
Scrapebox in particular really uses up a ton of bandwidth - you can tell when they are trying to hammer your site because page loading slows way down. I've taken to banning IP addresses to keep them away - they use proxies, so I just ban the IP of the proxy so no one can use it again (unfortunately there are loads of these proxies, so it's a never ending battle).
Once they've scraped all your urls, they load them into Xrumer which then starts to post automatic comments.
On maintained blogs, these go straight into the spam trap - On Wordpress, Akismet is getting better and better at stopping them.
But like the email spammers, because they are doing this by bot, they only need say 2% of their comments to "stick". They usually stick on a blog someone has abandoned, or one where the owner has neglected to update their spam-traps and only logs in once in a while to zap stuff.
Because G gives credit to links immediately, by the time the links are zapped or have dropped off due to the sites they are on expiring, they have created 1000's more.
If G could just put a moratorium on the time new links are acknowledged - say four months - then a) these guys would have to wait to see a return on their activities and b) by the time the moratorium was up some of the links would have been zapped by the site owners or otherwise dropped off.