I've seen that too, no doubt far more often and longer than you, both because of my extra years and because of being a steward.
In what instance of any of those injustices does any of that promote dishonesty?
In what circumstance would lying or stealing or being dishonest in any way be the better/smarter move than being honest?
Sorry, you are dead wrong here.
The company blows it with small minded tactics or decisions lots of times, but normally being dishonest will only excerbate the situation and the few other times you would only be denigrading yourself for a crapshoot,certainly no guarantee of being better off.
I have watched state panels finalize terminations on relatively weak cases because the employee maintained an obvious lie in the face of circumstances.
There is no faster way to cement the companies ire to fire and no surer way to put doubt in the minds of the union side of the panel.
If they believe you are being dishonest it hardly matters what charge trumped up or legitimate that the company is using because regardless of what you think about the individual ethics of the union big shots, they will not defend or save a liar and you are right, some of them (and some of the company managers) can spot a liar twenty miles away by the "takes one to know one" qualification, but that still won't save an employee caught or even strongly suspected of being dishonest.
That is not to say you act like you have babble serum in you and admit everything you think about the company or particular manager with baldface statements of
truth.
Honesty,integrity,discretion and diplomacy all have separate definitions, but none of them have dishonesty as part of those definitions.