Jane_Doe, Do you think having no follow links on all user generated content would help solve that problem?
I am not sure what you mean by that. I didn't mean to single out dodgy dofollow links as a probable cause. I just used them as one example out of thousands of possible reasons. You could also have things wrong like a cloaked page, hidden text, keyword stuffing, not enough content, off topic content (weight loss tips on a high ranking site on Dutch painters of the 17th century), duplicate content from another page within your site, etc. Anything that would give off a low quality signal.