Well this is something interesting I have noticed. When I come to India I travel on Singapore airlines.
First part is from Australia/nz to Singapore; the plane is new, service is good, I'm happy
Second part Singapore to India; The plane is a old one, things don't work, I can see the drop in service, not happy!
I am lucky enough though that if the seat I'm in has something that doesn't work they change my seat. Why? Because I don't travel on Indian PP and they give my seat to someone with Indian PP...poor guy.