Ah! The "I'm determined to find something wrong, so that I can have a really bad flight" passenger. A fairly unusual species, although becoming more common. Can often to be found in a business suit, and as ProM has noticed, tends to congregate towards the nose of the aircraft, but a species that can provide many hours of amusement for the cabin crew!
I have always found that the best way to deal with these people is to become more and more sickly sweet the nastier they get. They hate that!
It reminds me of a passenger on my flight that was determined to cause a fuss over anything he could. He'd ordered a Kosher meal, but when I took it out to him he kicked off saying he didn't want that rubbish. No problem sir, I have a spare standard meal and I'll send a report to the exec club immediately for you, Sir! Then he didn't want to put his seat back upright while everyone else ate, so having empathised with him in my best, symathetic, "poor you, you must be so tired being such an obviously important and busy business man", manner, I found him a spare seat so he could sleep. This went on through the whole flight. Everything he complained about, I found an instant solution, (good luck was on my side!) and he got more and more frustrated. Finally, when securing the cabin for landing, he was obviously going for anything he could think of and yelled at me that my PA's were crap and he couldn't understand a word. Well obviously, I was very apologetic and just before I sat down, I did the lights for landing PA, which went something along the lines of;
"LADIES AND GENTLEMEN....I WILL NOW BE DIMMING THE CABIN LIGHTS FOR LANDING....THIS IS NORMAL PROCEDURE......"
before sitting down and beaming at my disgruntled passenger whilst mouthing, "was that OK?" to him! The giggles from everyone else in club, who were heartedly sick of this man, not to mention the shocked faces of the other crew peering out from the rear galley, made it worth every second!
Sorry, I went off on a bit of a tangent there, but in answer to your question, I'd have to say don't get involved. By saying something, you could be giving these people further fuel and that's exactly what they want. We, as crew, are used to dealing with this type of situation and know not to indulge their little tantrums. Think of how you'd deal with a 2 yr old, minus the naughty step, and you can't go far wrong.
Jsl