[Yahwe]

well we'd certainly never vote in a politician who wore flip flops.

but back on topic the point you raise is the problem that either:

1) the majority votes in a politician because they have used the election process to analyse how competent that man/woman is and by voting them in essentially say "we have decided you will know best, please feel free to do as you wish"

OR

2) the majority votes in a politician on the basis of the promises/commitments they have made. ie the populous at large votes in the politician because said politician has promised to build a bridge or knock down a decrepid building

traditionally britain uses method 1) (despite the emergence of manivestos) because we do not directly elect our government. i

believe the US uses method 2) - because you do directly elect, if not your whole government, at least your sovereign. thus specific promises are important and evidence that you can not keep a promise is a bad thing - hence flip flopping