The only way for your website to not have ANY fingerprints on it, is for your website to be on an inTRAnet.
No matter what you do, robots.txt, everything-is-an-image, whatever, your website WILL be spidered / have some sort of fingerprint.
My recommendation is to reevaluate what you would accomplish with this "script" and if you determine that this is ABSOLUTELY a real need and real enough to, 99% chance, lose 500$... then go for it.
I may of miss-understood you. If that is the case then my other interpretation is that PHP does not have the ability to erase those variables.
Last edited by TFlan; 01-08-2013 at 03:54 PM..