1、Too large a percentage of your links are reciprocal 2、Lack of high quality inbound links 3、Too large a percentage of your inbound links are not relevant to your site topic 4、No outbound links 5、Outbound links to poor quality sites 6、Too large a percentate of your outbound links are Nofollowed (note:does not apply to blog comments and forums, where this expectedbehavior) 7、No coherent topic for your site 8、Too large a percentate of your pages with duplicate content 9、Too large a percentage of your pages with minimal content 10、Titles are duplicated 11、More than 5 keywords metatags on your pages 12、Meta descriptions are the same on every page 13、Keyword stuffing　 14、Hidden text, or almost hidden text　 　 15、Hidden Links, or almost hidden links　 　 16、Web server downtime too high