If someone lies to you on a regular basis, then how do you know if they are ever telling the truth or not? Logic 101
You base it off the evidence and not what B.S. they tell you.
I don't automatically believe either, but I don't assume they're lying either.
I evaluate the facts in hand and decide what I believe the most likely truth to be. In my own judgement, the missle theory is without facts to even be evaluated. There's an edited, inconclusive video of a vigorous contrail. That's it. That's the whole enchilada, despite what WND wants you to believe.
I believe if it was a missle, somebody would be able to prove it, or at least produce some shred of additional evidence to back up the theory quite easily. Nobody has done so. There is no other evidence of a missle launch because there was no missle launch.
I am more than willing to change my opinion, if somebody produces some facts.