I once, through excellent technical knowledge of the aircraft (Puma), diagnosed a persistent fuel leak from the tank. Everyone scratched their heads and gave their opinions, but I solved the problem. The installed ferry tank was 'on', and it was over filling (and slightly pressurising) the main internal tank. None of this is stupid.
I proved my theory to 6 or 8 onlookers by removing the filler cap! There's more. It was a non English speaking country, and I succeeded in buying fabric softener powder rather than washing powder. There's more. I only took one flying suit!
I learned about being a dick from that!
CG