If Bush was deceived by Saddam, and the WMD's were moved to Syria or overlooked in Iraq, Bush still bears the responsibility for the failure to locate the WMD's, being hoodwinked by Saddam into believing there were no WMD's and for letting the WMD's fall into Muslim hands
If Bush was not deceived by Saddam, he bears the responsibility for failing to realize that Iraq did not have WMD's and consequentially overreacting. He had three years and the world's largest intelligence network at his fingertips to figure out whether Clinton's CIA guys were right or not.
Again, whether there were WMD's or not is really a moot point here; Bush messed up strategically either way you want to look at it.