You want to avoid somebody like a Geraldine Ferraro, who's going to blowupinyourface because you didn't vet her well enough, or Dan Quayle, who also wasn't vetted well enough.
Whenever you start working for a company, there are a number of things to learn about during your first few months that can make life easier: how to make a new pot of coffee, who knows where the office supplies are, and any internal politics that could blowupinyourface.