Dishonesty is a sin; thus a moral failing. But its roots are deeper.
The world is in a spiritual war - between God and his allies on one side; and Satan, demons, and the mass of variously evil-affiliated humans on the other. And Satan's side hugely-outnumbers God's side.
That is the global state of play, as of 2020. It is a basic and essential fact of life.
But, of course, almost everybody is blind to the fact; just as they are blind to the fact of truly staggering levels and pervasiveness of dishonesty in public discourse - extending from the international reach of the mass-social media and global/national government; to the level of millions of committees, and billions of interpersonal interactions.
For such a moral sickness to have afflicted so many people simultaneously; indicates a deeper underlying cause.
And that cause is the condition of spiritual blindness and denial which has swept Mankind over the past couple of centuries - beginning in The West, but now seeming to include almost everybody, everywhere.
Consider that in the ancient past - from everything that is known - everybody perceived spirits, including 'the dead' and ghosts - who were present and active in the world around them. (The same was the case, if we can remember, in our early childhood.)
But now, almost nobody does - and the reality of such spirits is denied, and their reality-significance is excluded from public discourse (including most religions).
Because spirits are denied, evil has no objective reality; because the nature of evil is spiritual; evil just-is to be on the side of the demonic spirits who are opposed to God and God's creation.
If spirits don't exist, then evil doesn't exist - and therefore so-called-evil for Modern Man has been re-defined psychologically, subjectively and therefore relativistically. In effect; evil has now been explained-away.
Dishonesty too. Since honesty and truth are a product of God's creation - lies have no objective reality when creation is denied: when the universe is seen as value-free... just a collection of mechanical causes and mathematical randomness...
We can conclude that Men have changed. Modern Men sleep-through the spiritual reality of the world, in the same way that a sleeping Man is unconscious of what goes-on in the bedroom around him. The bedroom is still there, still effectual - perhaps dangerous; but the sleeper knows nothing of it.
However, this modern condition of innate spiritual insensibility is something we are 'born with'; it is an aspect of the modern condition.
Modern Men are, in this respect, spiritually differently-set-up than Ancient Men. Modern Men just do not (except in altered and impaired states of consciousness - drugs, delirium, psychosis...) perceive spirits, the dead, ghosts etc.
My understanding is that this insensibility to spirits is an aspect of the evolutionary development of consciousness - and happened because Men are destined to develop towards greater freedom, greater agency - and thus a more God-like consciousness.
In a nutshell, because Modern man does not spontaneously perceive them - Modern Man is free to choose - and indeed Must choose - to be aware of spirits, the dead, ghosts, angels, demons etc.
We cannot (and should not try) to choose to 'perceive' (see, hear, smell, touch) spirits; but must choose to be aware of them - to know them experientially.
(I say 'must' choose; because the alternative is this 2020 world of near-universal self-damnation.)
How does all this relate to honesty?
Well, honesty (for all its practical benefits) must ultimately be a transcendental virtue - pursued for spiritual reasons. This is because it is so often expedient to be dishonest - and anything less than the full intention to know truth and communicate it truth-fully is dishonest.
All forms of hype, spin, misleading, selectivity, exaggeration etc are In Fact dishonest - and indeed more morally wrong (because strategic and deniable) than many a plain lie.
And truth-full-ness is impossible in a world in which the spiritual is not known, and is denied. The spiritual Just Is a part of our world, a very major - indeed primary - part; therefore there can be no honesty when the spiritual is excluded.
There can be no honesty when the spiritual is excluded.
Or, to put it positively - to be honest we must know the spiritual realm.
Of course, knowing the spiritual is not sufficient to salvation - since we might know the spiritual and also reject God and Creation; know the spiritual, and yet choose to fight and try to destroy all that sustains God and Creation.
That is the demonic position - the spirits who know the reality of God and Creation yet have made an irrevocable committment to oppose God; and the devil is therefore correctly described as the Father of Lies.
Evil regards truth as merely expedient; therefore evil is always as dishonest as is expedient - therefore the world of evil is a tissue of lies.
(The Global System of lies, a Matrix of lies - a virtual-reality of lies...)
This is the deep reason why the side of evil (as represented by mainstream, world-dominant secular leftism) is incoherent: evil cannot be coherent!
But evil does not 'need' to be coherent, because evil's purpose is to oppose God, Creation and The Good.
Opposition need not be coherent, and it never is; it merely opposes The Good in whatever manner presents-itself; and justifies its evil using whatever excuse seems likely to be effective, here-and-now.
In sum - the fact of dishonesty everywhere, and all the time, is a consequence of Modern Spiritual Self-Blinding.
Which is a product of the choice (which almost everybody seems to have made - although apart from the demons, this choice is reversible by Christian repentance) to choose Not to acknowledge the reality of the spiritual.
Until we are again in a position where the reality - and significant, active presence - of God, angels, demons, the dead, ghosts and much else - are a part of our experience and discourse; then evil will remain dominant.
And this is a matter of conscious choice.
So every single person is ultimately responsible; there is no excuse of 'ignorance'.
Not-choosing is not-an-option.
You and I and everyone already-has-made a choice; but... that choice can be changed.