Years ago I was sitting near the front door of a United Airlines B727 in Chicago, when they started taxiing out I buzzed the stewardess and said I think there's a problem with the front door not sealing correctly as the amount of engine noise coming in wasn't right, way too loud when sitting up the front of the aircraft.
She ignored me but a few minutes later we returned back to the terminal and a technician arrived at the airbridge and got to work on the fuselage with a hammer and some special 'duct tape' and ten minutes later we were on our way again.
This was the second aircraft I had boarded that day to fly to Houston , the first one had about 10% of the seats full and I said to the guy in the aisle across from me "we won't be going anywhere" , sure enough the captain announced we had a technical problem (engines not started yet) and we got off the plane and waited for the next departure announcement.
A few hours later the departure lounge was overflowing with passengers (now late afternoon) and one guy was complaining that he had a reserved ticket and how come he didn't have a seat.
The response from the stressed out counter staff was "I'm sorry sir, the flight is overbooked"
Pax "But I MUST get to Houston tonight"
Counter staff in a drawly accent "Weell siiir , I suggest you fly ANOTHER airline"
Amen I thought !