Yes but, SNS3Guppy, just because one is arrogant, even angry and even rude does not make one incorrect?
The question can only be answered in the context of a specific situation. At times directness is not only appropriate but warranted. In most cases, decorum and professionalism dictate that a less candid, more diplomatic approach is preferred.
Does being arrogant, angry, and rude make one incorrect? By technical subject matter perhaps not, but with respect to resolution of a conflict, or establishing the company presence and imagine, yes, it does.
What I see too often here, and it's really a concern brought up by the original poster, are individuals who may not have a full compendium of aeronautical knowledge at their whim, who ask a simple, innocent question. Not uncommonly we see them beaten and bludgeoned by pilots who act as though the individual should have been born with a doctorate in aeronautical science. This shouldn't be.
Now sometimes we see the opposite. Recently a poster on the tech forum asked if he should believe his aircraft flight manual regarding landing distance, or "wikipedia." As you might imagine, this elicited a number of sharp responses, including my own. Later, the poster revealed that he was a 15 year old young man, most likely a computer game player, asking from a much more basic level...had he revealed this information at the outset, the response would have been far different. As it was, once his case was established, many able posters were quick to provide good information.
In other recent cases, during technical discussions regarding critical safety of flight issues such as rejected takeoffs, posters have jumped in with an absolute lack of understanding, immediately critical, and certaily detrimental to the discussion. One can understand then, when the lack of patience displayed by the pilots participating in that forum, exceeded their tolerance. Directness in such a case would be, and was warranted.
In other cases individuals have entered the same forum asking the most basic of questions...how does a jet engine work, what's a compressor stall, how is lift formed...etc. Clearly these are people looking for information, and in nearly every case it's given generously. A simple, easy to understand reply is warranted, and there's no need for arrogance, or rudeness.
The specific situation dictates.
Some years ago I experienced a passenger who was quite over the top. He screamed and yelled, turned a purple color, balled up his fists, and was spitting as he talked through clenched teeth. He became an unpleasant character. I made an intermediate landing, and heard about enough as he demanded that I go fly him where he felt he should be. He made a similiar comment as someone earlier in this thread...that he was my employer, that he was paying my wages, and that I would do exactly as he said.
In that particular case it was a chartered flight in a corporate type aircraft. He was paying a lot of money to go somewhere. I told him very calmly that I was grounding the airplane and the flight based on his attitude, that he was behaving unsafely to be flown anywhere, and that his flight was over. He screamed and yelled and eventually calmed down. I made it clear to him that I have only one duty, and only one concern as the pilot in command of the airplane; safety of flight. That includes his safety, and the safety of the airplane. The "I'm paying your wage" arguement just doesn't cut it for me. I'm the pilot, it's my call, my authority, my responsibility, my duty.
The passenger isn't paying my wage. My employer is. However, even in the case of my employer, nobody is paying me enough to compromise, and nobody is going to win any points with me by trying to throw that in my face. "I'm paying your wage" doesn't hold a lot of water with me. If you're my passenger I'll accord you all the respect that's due a fellow human being regardless of whether you're flying for free or paying a hefty sum, and I expect the same in return...as well as respect for my position and the duty is entails. Once that relationship is compromised, I will do my utmost to restore it. Failing that, in the face of a passenger or customer (or employer) who elects to go beyond being civil, one may quickly learn that my own determination will quickly exceed theirs, and it's a fight they're not going to win.
Diplomacy is far more than a good idea, and where applicable, works best. Where it's not applicable, there are other appropriate means of handling a situation, particular to each case...but this is never preferred...by me, my true employer, or the passenger for whom I will bend over backward at any given moment to please.