Why do we appoint people to be our advisors, put them in crucial positions and then not believe them or choose to ignore them when they advise us?

I was watching this documentary earlier on GPB by The Frontline, and it really got me to thinking. We have all these people overseas fighting the War on Terror against al Qaeda and the Taliban, but when it comes right down to it the powers that be don't seem to be listening to them at all. They ignore their suggestions, brush off their comments about what's actually happening and seem to be favoring the opinions of people who are sitting safely on the other side of the ocean.

How much sense does that make?