If someone gave you a perfectly reasonable and logically consistent explanation, what makes it right to automatically assume they're lying and substitute the wo

If someone gave you a perfectly reasonable and logically consistent explanation, what makes it right to automatically assume they're lying and substitute the worst possible alternate explanation? The point isn't that you have to trust 100% of what everyone says. The point is that it's a problem if you're trusting 0% of what everyone says and using that as an artificial opening to insert your own, alternative explanation in which you are the victim.