A lot has to do with the candidate. Hillary, for instance, went into coal country and told everybody that she was going to shut down the coal industry (something to that effect). Anyway, what happened is that she turned the entire area against herself! She was actually telling the truth and had plans to help those not working but never got that far. I suspect that she was grateful for actually surviving that one. I also remember the guy running for gov of Virginia. He was absolutely sure that he had won the election so he said little things like parents should have no rights when it comes to what their children learn in school - yet another Democratic error. I also remember Biden. He spent a lot of time making promises that never happened to the point where he was ignored. I have always thought his first year was a Biden who thought he was still a senator so he never told anybody what he had done and what he was doing. Kinda like keeping secrets whilst playing senator, I think. I have wondered, now and then, whether they were actually trying to setup a Trump situation for themselves where they could run their mouths with impunity. Hope they have come to their senses on that one.
On the other side Trump can say just about anything. He has his base and they will accept whatever he says and move on. I expect that the reason for their acceptance is their flat out belief in the man regardless of his shortcomings. He is, for instance, the very worst rich guy I have ever heard of. Daddy gave him half a billion and that resulted in 6 bankruptcies - one can only wonder!
Just saying..............