Excellent topic P....and a good question...how successful are historians at digging up the truth? Another question would be...are they interested in digging up the truth, or does each have his own particular agenda? I could find two entirely different renditions of just about any history we could think of in any academic library...no doubt. Revisionist histories abound, and many of them probably paint a clearer picture of the 'true' history than the standard narrative that we've been fed for years and generations.
I read about Bush's decision to withhold important documents recently, even fellow republicans such as Dan Burton 'Clinton-hunter' were appalled by this, but Bush claims to have done it for the national interest. Unfortunately, documents are regularly hidden from public consumption, and sometimes they are even destroyed. I'm fairly certain that the Bush administration isn't the first to instigate such activities, and we can bet he won't be the last.
With that said, I suppose it's up to us to construct history by our own endeavors. By that, I mean our own reading and research. The most limiting factor that each of us have in understanding ourselves and the human condition is lack of information...so it probably follows that the more you read, and the more variety of reading you encounter, the better off you will be intellectually and the more able you will be to make a balanced assessment of our history.