My understanding from my CCW class/instructor was this.
If they post a no carry and you do, and you get nailed by them, they call the local LEO, you get ticketed for something stupid, it is a justification for the state to pull your license - because you ignored their sign. That is in the law therefore it is the law...... IMHO....
I still carry into the PO and bank. Why would they find out anyway? That's why it's called conceiled..... I don't drink while packing either. That's another part of the rules we have to live by.