My husband uses the term "Liar's Convention" quite loosely when local, state and federal elections are in the news. You can only hope you make an informed decision, which can and is difficult to do. And then when you see your decision to vote for a candidate who didn't come through on their promises, well, I look at it this way.
If you are sworn to tell the truth in a court of law, and found guilty of lying, well then you can be convicted of perjury, which will send you to the slammer. (Martha Stewart comes to mind)
I think the same should hold true an ANY politician who will tell the public what he/she thinks we want to hear, and once elected, does nothing to come through on their campaign promises. That to me is the ultimate slap in the face to the their supporters.