amen.

The least likely...apart from any airline which is not a US airline (OK, and Aeroflot).

Mostly just ignore the grumpiness as long as the service is still there. But I guess if the attitude is making me really uncomfortable then the just straight out ask them if everything is ok as they seem grumpy. In my experience, this either gets them (and most other grumpy people) talking or they'll say 'no problem' and make an effort to seem normal at least then.

Avoid all contact.

As long as they provide the expected service commensurate to the class I'm flying without being rude I could not care less whether the FA is grumpy or not. Brightening up his/her day or whining about it afterwards isn't on my to do list. I'm not interested in their problems.

No, I'm an adult.

It might depend on the airline. On, for example, United, I'd be afraid seven of the above nine responses might get me arrested. If I were on an Asian airline, although the problem is less likely to occur, I'd be less afraid of spending the rest of the flight in handcuffs with some of the other responses.

I completely ignore the attitude and behave normally.

Mostly agree. I recently had an 8 hour flight, in a row 3 sleeper seat, with plenty of service interaction times. Nary a single smile on the entire flight. For every the FAs presented me (a hot towel, a beverage, a food course), the crew member received a "gracias." No eye contact, no "de nada, no hay de que, you're welcome" ever. Where I ceased behaving normally was near the flight's end later in the second service, where I no longer thanked anyone, and didn't when leaving the plane.

I do not believe it appropriate, at least for myself, to cause in incident that "interferes with the crew," which these days, could mean a simple complaint, that lands you meeting the authorities, ending up on a no fly list, or similar.

I've dealt with my fair share of rude FA but since I only need to see them for less than a few minutes for food and drinks, I don't really comment or say anything.

When I picked my mom up from the airport recently, she told me on her flight up the FA seemed to single her out specifically. She said she had absolutely no idea what she did, assumes maybe her resting face must've looked mean and the FA went and was rude and passive aggressive to her the entire flight. She was in first and said she doesn't expect any sort of special treatment, but couldn't understand why he made her feel like such a bad person when he treated everyone else with a smile.

Hearing it upset me because she's one of the nicest people ever and doesn't ever cause a fuss.

But regardless of how bad someone's day is, it is their JOB. They are providing a service, and if they decide to be rude or give attitude, then they can't expect to not receive the same in return. I'm a super passive aggressive person, so had I been with my mom on that flight, I would have ended up calling the FA out.

Depends on the level of grumpy. I kind of get it. The public sucks, and the job isn't easy. I can forgive them alot.

And I would NEVER chastise one. That's just sanctimonious and arrogant.

However, in the event that one REALLY crosses a professional line, I would absolutely report it. Either to a station sup at the destination, or to the airline directly..although they tend to ignore that stuff due to volume from Ma and Pa Kettle who think their tea was too cold.

Normally, I just make sure I don't add to their crappy day. I may even be friendly and give a smile and acknowledgement. Please and thank you.

There have been some incidents that crossed the line with me over the years. Mostly not from grumpiness, but from shenanigans like allowing an NRSA to try and poach my seat, or treating me poorly because she knew the NRSA I booted from my seat and she made sure to be as curt as possible and screw up my food and drink orders. I also had a bizarre incident about 15 years ago where the FA would proselytize about jesus to every pax who would listen. Good news this, he loves you that each time she served a pax..I am sure I was not the only one who complained about that. She was far from grumpy though. I wish she had been.