i almost hate to do this but if your going to go deeply into "honesty" and define it as "telling the truth" then it pays to question what is "truth". Each witness will have their own interpretation of what was the "truth" and part of the "truth" that they witnessed will depend on the baggage (good or bad) that they carry. There are simple truths such as my wife's ass is just a bit big on which we might all agree (God help me if she reads this) and there are not so simple truths on which we might find it very difficult to agree. And somwhere here I think we get into the arena of belief systems; whcich is why "honest, sincere and intelligent people" will still find room to disagree.
If we could deliver the "truth" as we see it with just that modicum of knowledge that it is possible that we are wrong or that there has been a misinterpretation of someone else motives perhaps we could be more "honest" withou hurt than we customarily are?
But I could be wrong!