I’ve reported aircraft related issues to cabin staff twice over the years, both on B737, but different times and different airlines.
One was in Hawaii, just before engine start on a windy day. A large sheet of plastic wrapping blew off a nearby pallet and lay on the ground just in front of the starboard engine intake. The possibility of it being ingested was obvious. I advised a cabin attendant who never even looked out and just casually advised me “Oh I’m sure it will be ok if it’s just plastic”. Brain dead ignorance. Thankfully it blew away again just as that engine was being cranked over.
The second time was again an engine issue, as we reached the cruise over the North Sea, inbound to U.K. I noticed that a large quantity of fresh oil was trailing back from the inboard side of the engine cover. I pointed this out to cabin crew who gave a cursory glance out of the window and tried to resolve a possible engine failure by telling me that “Oh, they all do that, Sir!” My answer was that the Jet engines on my aircraft never did!