>I'ts written, works well and cannot be detected.
I seriously doubt your claim, because you assume that the search
robot can itself be detected, and that their programmers are not
aware of these methods. Both assumptions are false.
It would be very easy to foil this technique. If the script relys
on the robot giving its name (useragent), one can change the robot so it
claims to be any of the popular browsers. If the script relies
on the request coming from a certain IP address, re-assign the
robot to a different one or run it through a proxy.
Only slightly harder to do, would be to have one robot requesting
the pages and a follow-up robot claim to be a browser. If
the pages are significantly different, there was a robot stuffing