Imnotadoctor writes that Google still seems to reward link spammers.
For those of you who aren’t familiar with the concept, link spammers will build a site and then purchase or otherwise collect thousands of links from other, unrelated web sites, for the sole purpose of improving their search ranking.
Google frowns (glowers, actually) on this practice, but it’s not always easy to detect.
If you find an instance of link spam, or any other attempt to fool the search engines, please report it using this form.
Link spam is the toughest to stop – no guarantee Google will act on a report. But they are always improving their filters and any reports will help.