OK I am wrong that the inspectors were happy that Iraq had provided satisfactory evidence of the unilateral destruction of some programmes just after the war. From Hans Blix's report to the Security Council prior to the war: "While Iraq claims, with little evidence, that it destroyed all biological weapons unilaterally in 1991, it is certain that UNSCOM destroyed large biological weapons production facilities in 1996".
I remembered reading about the evidence Iraq supplied for this and there was quite a lot of it so I don't agree with his reference to "little evidence"; but clearly what evidence there was was not regarded as satisfactory.
Blix Report