We can't judge another programmer's abilities in a 60 minute interview
You can judge programmer's ability in 60 minutes.   Can someone program?  60 minutes is way more than enough.   How great of a programmer are they?  You're going to need more than 60 minutes, unless already had a chance to look at their prior code base.What's difficult to judge is, are they organized?   are they hard working?   how do they handle stress?    how's their communication and attitude?    do they write great documentation?   do they test their code?  are they a great team player? how creative are they?Due to time constraint of an interview, someone might be more sloppy than usual.   Their might be the interview stress which is different from regular work stress, interview stress can impact their communication, etc.   But if we focus plainly on technical skills, you can flush that out in 60 minutes.I'm a hiring manager, and I have never failed in hiring someone who didn't have the required tech skills.   Technical ability I can always hit spot on, the tough one is determination and soft skills.    Some of the folks I took chance on, who displayed terrible soft skills during interview turned out to be champs, communicate great, work hard, etc.    A few that were very eloquent during interviews were a disappointment, sloppy in development, poor communication in practice, etc.People also grow, so someone that was a bad fit/interview for you, could in a few years grow and become great.   Potential is also difficult to spot.