I hired a seo guy for http://www.iseekblog.com , another member of cap has a free bloghosting website and can confirm that my site was top 10 with his for free blog ,free blogs and free blog hosting. the seo guy used alot of porn stuff to gain backlinks ,i paid him only 2 months for off site seo and the site got nailed in google and right now the only keywords i am found for are sex related.So sorry to burst all the bubbles here but it IS possible for somebody to take us down by doing some bad linking on our sites.
I stand by my original post that using offsite seo services sometimes can kill you if they use free links from bad neighbourhood forums.This is why i will NEVER use another seo company again for any sites that i consider valueable and make me great income ,these days everyone is a seo expert if they can get one keyword that nobody will ever type in a search engine box 
Trust me it is better for you to read and try to learn on your own and dont forget my golden rule -you have to spend money to make money.