The whole political process in a democratic environment nearly
  ensures several things to me:

  a) politician needs to look good in front of a lot of people
  b) people expect perfection
  c) people will only vote for a candidate with acceptable
  imperfections.
  [perfect imperfections]
  d) people like idealism because ideals are perfect things,
  untainted.
  e) a polititian's *actual* amount of control/influence is
  severely limited in an environment where there is give/take,
  push/pull.

  So therefore:

  a) politicians must polish their image.
  b) politicians must appear perfect.
  c) their imperfections must be timed correctly at the revealing
  and must be of the proper sort of imperfections to endear
  themselves to the public
  d) politicians must only speak of broad ideals that they cannot
  directly control because:
  e) anything they try to change they will likely be unable to.

  If you notice most campaign promises, they _tend_ to be about
  the exact things they can do nothing about.

  They may have one or two things that they focus on that they
  *can* effectively accomplish.

  But the rest? are linking the image of themselves into the
  ideals of the people that they wish to have vote for them. The
  politician wishes for the best of all things, just like the
  people who vote for him/her do.

  So in short, they are typically voted in as "carriers of a
  dream" but not actually changing much related to accomplishing
  that dream.

  I know I'm a little harsh on politicians. But they tend to make
  promises they can't keep, and their principles are easily
  acceptable humanistic principles in general, or they are ones
  that are designed to reflect what a large enough portion of the
  voting population already believe.