Most of us have done a very limited amount of vetting candidates, though of course we size them up all the time. But there is a difference between choosing among a group of candidates from their media presentation and actually vetting them. Vetting is a systematic process for discovering the strengths and weaknesses of individual candidates before offering them assistance.
The process of vetting is especially important to Precinct Committemen, who are the ultimate grassroots activists. As members of political parties, committeemen (or precinct captains, delegates, or whatever they are called in your state) are the first line of defense in keeping the bad actors out of politics — and in identifying good public servants, as well.
I divide the key factors in vetting a candidate into Commitment, Policy, and Retail Politics categories. In breaking down those factors, realize that they are related and often in conflict, so don’t get caught up in the categorization. A candidate sometimes will have to choose between his commitment to getting elected, to his principles and policies, and how to speak to a given set of voters on particular topics.
Another note before digging in: candidates lie. They forget, obfuscate, hedge, hide, engage in wishful thinking, and try to put the best face on things. A good vetting process is designed to alert both the candidate and the investigating committeeman to potential pitfalls. It is an essential part of filling local offices and developing a campaign strategy for the selected candidates.