Sure, a fellow running for county commissioner in rural Mississippi is more likely to say what he really means, but that's because he has far less money to employ a campaign director and probably knows his constituents personally. But at the higher levels wherein candidates have to convince literally millions of votes, I put zero stock in words spoken behind a podium, in front of a camera, or behind by a microphone.
To truly determine what a candidate might do while in office, you have to look at their past. What did they do when they weren't lighting candles, playing Lionel Richie records, and trying to talk your vote out of its pants and into bed?
What did the candidate do when they had the power and the opportunity to achieve their agenda? What bills did they author, what bills did they co-sponsor, what amendments did they attach to other bills? How effective were they at getting their legislation passed?
Well, someone has done the hard work for you. Here is an article comparing Senator Clinton's and Senator Obama's time spent in their previous offices. It is a long article, but probably the single most informative piece of journalism concerning the Democratic candidates.
I won't tell you which candidate it favors, because you owe it to yourself to read this article. Honestly, I was still fairly undecided before reading it and have now made my decision. I still have more research to do on McCain before I am sure, but my leanings are Democratic to be sure.