It isn't a matter of believing or not believing, it's a matter of verification. As a rule, no matter how honest you find someone to be:
1. If you can check what they are saying for yourself then you should do so -- the person you trusted could have been wrong, and you'll look pretty stupid if you just blindly assume they were right and discover that they were wrong after all (regardless of the reason for the mistake).
2. If you *can't* check what they are saying for yourself then it's surely sensible not to allow such anecdotes to influence your view of the world.
For example, with respect to fender's stories, there is no way I can possibly verify whether it even happened (I have only his word); there are other explanations for the story, of varying degrees of plausibility; and there's no way I know of to replicate the incident. This isn't an assertion that Fender is a liar, or deluded, or whatever other adjective you'd care to invent. It's just an assertion that I have no desire to let someone else's personal accounts influence my view of the world if I can possibly help it.
If and when such an incident happens in my life, maybe my opinion will change accordingly -- although, as with other people, so with myself. I'm no more immune to cognitive biases than anyone else, so it also seems sensible not to take everything I think I see/hear/experience at face value either. Or, at the very least, nobody else should.