aristotle - 5:17 pm on Mar 12, 2011 (gmt 0)
It should be noted that the sudden acquisition of a lot of spammy backlinks might not be the fault of the website's owner. Last year one of my sites suddenly picked up more than 2000 backlinks from spammy .cn (China) domains. I believe that they were auto-generated by some program or script. I was worried that they might hurt the site's rankings, but luckily that didn't happen.