Anyone familiar with google bowling will know its when a competitor dumps links on your site to cause you a penalty. Google Bowling version 2 is where a competitor pays to increase your bounce rate and to devalue your site and get it Pandalized. Look for a spike in your analytic followed by high bounce rates
I certainly have a paid flow of traffic coming from some European cell phones that I didn't pay for and my traffic is down from google (but up from other "good" sources). I question google's ability to adequately rank 10 trillion or so web pages, especially when you factor in things like this.