[potatolicious]

Incognito is a pretty thin layer of privacy. What many systems will see is this:

"User foobaz123 logs in from IP u.v.w.x. Here we have a no-cookie session from IP u.v.w.x. This is probably foobaz123"

Any identity management system of modest complexity can do this with fairly good accuracy. So while they don't have you confirmed via an authentication cookie, it's certainly a far cry from total anonymity.