Dealbreakers for hiring a programmer

You are an experienced and settled member in your company. After escaping a series of layoffs, you have reached a stable employment position, and are considered a valued employee. As one of the more seasoned in the workforce your knowledge of recruitment is considered essential. Thus you have been tasked with the responsibility of finding a new programmer for your team. What red flags will you watch out for in your slew of young and eager interviewees?

I've hired two programmers at my company. The last one was a cute Chinese girl with Lisp on her résumé. We've had three lunch dates and went out to karaoke last week. This Tuesday night she's coming over to my place to cook yakisoba chow mein. Wish me luck /prog/riders.