I have been fortunate that in all my travels in the past, I have had only 2 major incidents with my luggage.
The 1st was when my bag was mis-directed and sent to Hawaii while I was coming back from LAX (Los Angeles) on United Airlines. From this incident and from the level of service provided by the airlines, I swore never again by UA!
The 2nd, and more heartbreaking, was a case of folly on my part. Returning from work in Tokyo, I was too lazy to lug my laptop along. In those days, a notebook weighed like it was made from bricks. And I stupidly thought that if I padded it enough and placed it in the middle amongst my clothes, it should be okay. My $2000 NEC never made it back home alive. sob sob.
These are the unglamorous side of flying. The lost luggage and the anxiety waiting at the belt must count amongst others, like tension at the custom check and immigration counters. Luckily I have not had any occasion to make claims against any airlines yet.
One of the great thing of the internet now is the speed at which grievances against bad service is quickly made known. Here is a incident which happened in the USA which sent United Airlines reeling.
Dave Carroll, a musician, was refused boarding unless he checked in his Taylor guitar. Something he had never done with other airlines as the guitar was his bread and butter. United told him simply he can't board if he won't check in the guitar. And guess what happened?
From his window seat, he actually witnessed the baggage handlers throwing his band's instruments on the tarmac, including his guitar!
He spent nearly a futile year trying to get the airline to compensate him for the damage. In exasperation, he decided to make a grievance video and post it on the internet. I must say it is one of the best complaint letters I have ever seen. Here it is from Youtube.