seoskunk - 10:20 pm on Feb 22, 2012 (gmt 0)
I have posted twice about this zombie traffic. In my case it sent bounce rates through the roof and visitor stays through the floor so if thats a factor in rankings its a type of google bowl at the site (but probably I'm paranoid). I did post this when I saw traffic was zombie.
To try and prevent this I put in a spider trap and my traffic dropped and bounce rate went from 70% to 38% and time on site also increased longevity of visitors.