Remember; the way you approach the evidence usually determines your outcome.
And conspiracy theorists usually tend to have a desired outcome in mind when explaining a conspiracy. Truth is what a theorist looks for, but conspiracy involves secrecy, and the desire to uncover truth becomes greater because of the secrecy.
Here is where the problem begins...
Conspiracy theorist already have an answer in mind when approaching evidence. But unlike a scientist who uses evidence to dictate a conclusion, a conspiracy theory uses evidence to shape a conclusion.
Much in the same way a lawyer is picking and choosing the evidence to shape their argument and make it stronger.
Seeking out a possible explanation for 9/11 or JFK's assassination can become a never-ending search because each new piece of evidence creates a deeper conspiracy, and can potentially lead us further from the truth. As I mentioned earlier, conspiracy theories are just a hypothesis of what could have happened.
But once truth is found, does a conspiracy theorist stop looking for answers? What if they are not satisfied with the results? And what kind of results are satisfying to a conspiracy theorist; the most outlandish story or the most sensible hypothesis?
Obviously, conspiracy theorists desire something when searching for an answer. But that something is "truth" only as they would understand it.