With local or state candidates you should be able to call and talk to them. Ask questions, but phrase the questions so that the candidate can't tell which side of an issue you're on. If you can't talk to the candidate, look at his or her record. If the candidate hasn't held office before, look at the organizations he's worked with or belonged to.
I try to talk to candidates as much as possible. I called one judicial candidate a few years back and, after enough questions, learned that she thought only the police and military should have guns.