When I was a young wiseass along for a ride on a 732, we were stuck at the gate due to a fuel leak from engine number one. Small amounts of fluid make big puddles, but this motor had a drip and a good size puddle below it regardless. Captain told us SLF that he was waiting on maintenance to come have a look. About an hour later, the desired maintenance staff hadn't turned up, but the captain had decided to start the engine under the theory that the leak would "seal itself". I thought that a little bit odd of a thing to do with an airliner full of people, but I was young and "wise" and the captain was certainly old and wise.
I got a rise out of some passengers (some laughing, some looking worried) by loudly inquiring what facts had changed that made it safer to just give it a shot an hour later with an even bigger puddle of fuel under the wing, and what exactly the plan was in case the leak decided to get worse. Uneventful flight of course, and I was a loudmouthed idiot, of course. One understands why flight crews choose not to tell the SLF anything of value...