How does realpolitik affect our perception of politics?

 (My brief answer in Quora).

It reinforces the notion that a great deal of political decisions are made on utilitarian/self interest grounds thereby dispelling the naive notion that morality is the overriding deciding factor.

From a cynical perspective it runs roughshod over the simplicity that urges us to see political figures as ethical sources of leadership. They rarely and more often than not will disappoint.