A little story from my side for you to read.
On our flight back from Mexico to Germany, Oliver and me were sitting at the 'three seater' at the window. The bigger airplanes are divided in three sections; on the outer sides there are three seats and in the middle there are 5 seats.
The window seat was still empty and we were both anxiously awaiting our travel partner. We both have had nasty experiences with people not using any deodorant, making weird sounds (snoring, farting, etc.) or talking to you continuously.
When our guy approached us, we were relieved. No weird smells and he looked quite decent.
It turned out to be a continuous complainer. He was downgraded from first class to second class. Nothing was good enough for him. We were sitting at a compartment without chairs in front of us. Oliver was happy that he had enough leg room. I was happy that nobody in front of me would put their chair in my face. But our lovely friend was complaining about everything and kind of spoiled it for us.
I tried to be nice to him by helping him where ever I could. The stewardess was afraid of him and was doing everything possible to help him. Luckily I was sleeping most of the time so I didn't have to put up with his bad mood all the time.
He did give me the feeling that nothing in the second class was good enough for him and that he was better than us and deserved more attention. In a way he was right to be angry since he probably paid for an expensive ticket and got downgraded to the second class, but it wasn't our fault nor the stewardess'.