The Iraqis have, in the past, proved to be quite competent at hiding forbidden items. But they have relied a lot on artificial delays and changing the rules of who can go where. The current inspectors are playing by new rules, that threaten to unleash an American invasion if there are any delays or evasions. In the past, the Iraqis would do things like arrange vehicle breakdowns or even vehicle accidents to delay inspectors. The Iraqis insisted on advance notice, and were then caught, at some sites, still emptying the building of incriminating evidence.
But the Iraqis can still bug the inspectors quarters and use all manner of espionage efforts to find out where the inspectors are going next. Moreover, many of the new detection instruments can be bought on the open market and smuggled into Iraq. This may already have been done, with the Iraqis using these instruments, and changing the shielding and sealing of forbidden sites to remove sufficient traces of forbidden material so that the instruments won't go off.
There is also a potential problem with many of the inspectors from Europe, where anti-U.S. and anti-Iraq invasion feelings are high. There is some fear that many inspectors are ready to give Iraq a clean bill of health, no matter what is found.
The Great Game of Detection and Deception began as arms inspectors made their first visit to an Iraqi site. The Iraqis did not delay the inspectors, nor did the inspectors say if they found anything. The inspection process, which won't begin in earnest until after the December 8th deadline for Iraq to declare whether or not it has any forbidden weapons. After that, it's up to the inspectors to try and find forbidden weapons, for the Iraqis to keep them hidden. Both sides have had four years to get ready for this. The inspectors have new and improved instruments for detecting nuclear, chemical and biological weapons. The Iraqis have had four years to figure out new ways to deceive the inspectors.
The Great Game of Detection and Deception will go into high gear after December 8th, no matter what Iraq admits, or denies, having.