I knew it was BS when I heard Chenney say "there's no doubt that Saddam has WMD's".
AFAIK, there was never any intelligence that removed all such doubt. At least I never saw it, including in Powell's UN presentation. This BS just kept getting reinforced as time went on, especially at the end as the inspectors were getting kicked out by us in the rush to invade. I also knew the Saddam-Al Qaeda connection claim was BS because why the hell would Saddam, a secular "socialist infidel" in the eyes of Bin Laden, want to cooperate with the group? It made no sense.
As to where the WMD's went, my belief is that they were all destroyed, some secretly. Saddam was walking a fine line between complying with the UN and not being seen by Iran and other adversaries as a weakling ready to be rolled over.