Me and the missus were talking about this very thing yesterday.
It was in fact in relation to upgrades actually but still on the subject.
Situation:
PAX gets on with family or on own, wants upgrade as sees there are spare seats in club and because are seated apart or not desired seat etc etc etc. No seats left in economy to move them to.
Now... PAX - imeadiately gets the arse and starts shouting / waves exec club card about (no-matter the colour) / DEMANDS I give them what they want.
The chances of that passenger of getting what they want from me now have gone from 50/50 (if the situation is warrants an upgrade I'm happy to do it)......to NIL!!
Getting the arse and shouting at me will not get what you want, in fact it will get you what you deserve and what you paid for - a seat in ECONOMY.
Nice people get upgrades - ****ers don't.