Apparently, here are some of the allege factors that could affect your site adversely
* Participating in reciprocal link scheme
* Contents that remains the same without updates for a long time
* Too many links from articles websites or poor link quality
* Links from sites that seemed designed just to sell text ads
* The usual black hat SEO techniques such as hidden text, hidden links, inappropriate redirect etc
* Your site should return over 20,000 keywords when type in Google
* Lack of repeat visits
* Visitors exit your site immediately they got there
If you hear or observe any other factors please post it here
* Participating in reciprocal link scheme
* Contents that remains the same without updates for a long time
* Too many links from articles websites or poor link quality
* Links from sites that seemed designed just to sell text ads
* The usual black hat SEO techniques such as hidden text, hidden links, inappropriate redirect etc
* Your site should return over 20,000 keywords when type in Google
* Lack of repeat visits
* Visitors exit your site immediately they got there
If you hear or observe any other factors please post it here