I think it depends a lot on the role and company size. If it's someone who's joining as a first employee and you're going to be spending 10+ hours a day in the

I think it depends a lot on the role and company size. If it's someone who's joining as a first employee and you're going to be spending 10+ hours a day in the same small office, I think it's very prudent to learn as much as possible about them and determine if you'll be able to work well with them. If it's a larger company (read: not an earlier stage startup) then I don't think it's as necessary, but I'd still probably do it to vet them a bit.