dstiles - 8:03 pm on Apr 9, 2012 (gmt 0)
The fact that bad bots collect and return cookies is one very big thing in cookies' favour. The cookies (temporary session in my case) are often returned through IP-hopping, which makes it easier to trap such activity.
A very good way of over-coming the problem of GA cookies is to not use GA. I decided long ago they were too evil to live and GA was one of the very first things I decided against.