Intelligence unknowns

Can we really trust that the intelligence agencies get it right?  I have been a big critic of the CIA because they have gotten much of the advice that they give to the political branches of government wrong all the way back to the Vietnam war.  Now they are saying that Iran has stopped its attempt to develop nuclear weapons.  I remember how wrong they were about the Soviets during the 1970's.  I do not believe that we know what is right and this is the real problem.