If we make bets on what our representatives will do, it is very similar to bribing them to do what we want them to do.
Representatives will not have any legitimacy after truthcoin exists.
Very similar: http://forum.truthcoin.info/index.php/topic,168.msg817.html#msg817
So I don't agree with your premise.
But, more interesting, aren't representatives already controlled with bribes?
Bribing politicians is currently not well suited for crowd-sale. Lobbying is only done by people who can do it in bulk. This makes monopoly more prevalent.
If we used truthcoin instead then the politician who promised to lower minimum wage wont get his bribe unless minimum wage actually gets lowered.
Whether or not the politician creates a market for bribes, people will make fake markets betting against themselves for every politician. This will protect the handful of people who actually cheat.