A few years ago I was in Vancouver for an event. The after party got a little out of hand, and despite setting multiple alarms, I slept through them and woke up at the exact moment that my flight was scheduled to depart. To their credit, Westjet simply said "get to the airport as soon as you can, it'll cost you a $40 fee, but we'll put you on standby until there's a flight with room on it."
So the one time in my life that I totally deserved and expected my indiscretion to cost me hundreds of dollars, it only set me back $40. Plus the humiliation of being "that guy" who reeked of booze, smoke, and who knows what else. Good times.
Westjet came through for me that day, but I'm sure there were a few passengers sitting nearby that cite their experience as a reason NOT to fly with Westjet.