Civil servants are often very smart, and sometimes very bored. Also, unless they are in a position where they regularly face the public, talking to "civilians" can scare them a little - they don't want to be accused of stuffing up. (As long as you are talking off the record, not getting written advice - they hate paper-trails. Written advice is to "double check" that it's all OK).
They can really go out of their way to give free advice.