aristotle - 11:54 pm on Aug 29, 2012 (gmt 0)

1. Bounce rate up from 48% to 75% 2. Visitor time on site down from 3.48 to 0.35 3. Spam increase and Zombie Traffic 4. Returning Visitors down by 30%

This is probably due to poor targeting. You're getting traffic mostly from search terms that don't match the content of your website. Maybe it will take time for the algorithm to determine what the best matches are.