Politeness costs nothing. Rudeness is not acceptable in any environment, especially in a customer service environment.
And as a Customer, I don't care what the day of the FA has been like, what has happened to them personally, how busy they are, or any of that other stuff. They are there to provide a service, and to serve me. Politeness should be automatic. If you can't answer a question, say so in a polite way, offer to find out, or say "I'm sorry, but I don't know. I am busy at the moment, but I'll see if I can find out when I've finished this" or similar.
So if they had said what was mentioned above to me - a complaint form would have gone in.
Note - I want politeness directed to me (the customer) and also thing that this is a 2 way street - so I am always polite to them. BUT I am the customer, and they are there to serve me. This is not a 100% equal relationship.