There is a spectrum in American politics:

Personal ideology voting <----------> Constituency voting

(A third part of the spectrum, not really applicable in American politics, but more common in parliamentary countries, is party voting, and this applies when voters vote for an MP, not really because of the person's views, but because of the party views.  This is more common in countries like Canada and Britain, where the end result of voting is to get your party either into leadership or official opposition.)

I personally fall on the personal ideology side: I believe politicians should vote their personal beliefs because of our republic system of government; this does not mean that those on the other side of the spectrum are "wrong", per se.  Constituency voting is fine; I just don't agree with it.