Search the company on Facebook, the internet, to see some pictures of the offices at an usual workday.
Don't come too overdressed to a job interview, if the employees all wear casual clothes.

Looks like there's a story behind this suggestion?

@party101 well, kind of. Didn't affect me, since I looked at my employers Facebook page first,
but some appliers coming to an job interview here are dressed like they are going to the OSCAR awards as nominees after their job interview.
Just slightly awkward and weird for everyone, since even my boss wears casual clothing

But what if (this is my case) your personal style is to wear suits all the time?

@linuxxx well, then it isn't that awkwad and weird for you ^^