Honesty is not saying whatever you think.
Unfiltered commentary isn't a higher standard of truth, it's a lower standard of care. The useful version has two components at once: you're direct about the thing, and you're clearly on the person's side while you do it. Drop the directness and you get warm vagueness that helps nobody. Drop the care and you get accuracy delivered as an attack, which is reliably ignored — people don't act on information that arrived as a blow.
Most dishonesty is omission.
Almost nobody in business or family life is lying outright. They're rounding off, leaving the sentence out, letting a wrong impression stand because correcting it would be uncomfortable. That's why honesty is harder than it sounds: the failure isn't something you do, it's something you don't, and there's never a moment where it feels like a decision.
People want it more than you expect.
This is the most consistent finding in the research and the most counterintuitive. Across situation after situation, people asked to imagine giving hard feedback underestimated how much the other person wanted it — and the underestimation was largest for the things that mattered most. The awkwardness is real. It's just yours, not theirs, and it's smaller than the cost of them not knowing.
The hardest person to be honest with is yourself.
Everyone else you can at least see clearly. Your own reasoning arrives pre-approved, complete with reasons, and it takes deliberate effort to notice that you've been building a case rather than assessing one.
That's what honesty is — not a personality that says hard things, but a refusal to let people operate on information you know is wrong.