I was flying out of USA one night, on board an airline that my daughter used to work for (as "staff" PAX) and noticed ice creeping across the wing as we taxied out. I alerted a Steward to this and one of the Flight Crew came to take a look, with the result that we taxied back for a repeat of the de-ice.
I once pointed out fuel leaking out of the wing of a Delta MD-80 while in cruise, flight attendant consulted with flight deck and came back with the reply of it being normal, "probably just overfilled."