Imagine you smoke marijuana or something. someone tips off the authorities. you go into negotiations regarding the right to inspect your house. They give you a list of rooms they check on different days and the order in which they will be checked. Simple solution, you move the joints from room to room. no problem there (satellite images of trucks coming and going from inspection sites days before inspections occured).
authorities get upset, and say they will take over your house unless you give up the dope. They give you MONTHS of warning, saying "you better do this or else!". Simple solution, get it out of your house, give it to a friend before they come and do anything (tons of anthrax found in Syria by the border. anyone think they made it there?)
Could we have done it better? It would have been difficult. unannounced inspections, forced entry into the palaces would have been a start... I try to mention these things when I hear "there were no weapons". They also had long range missiles which were "illegal" by UN sanctions, but I'm hearing nothing of that. No, they are not nuclear or biological, but still against sanctions. I think things could have been handled a bit differently, but I prefer to discuss these presuppositions before drawing out the discussion of "why did we go in".
On the concept of "faulty intel", would you rather we get the best info we can and act on it? could this have in fact prevented 9/11? If all info says "they have this stuff", what should we have done? disbelieve it?