I've done it many times, and used to advocate it as a good practice. Then one day I was carrying my freshly filled bucket, and bumped the spigot into a door jamb...suddenly my Old Speckled Hen clone was pouring onto the floor! For a moment I thought I was going to have to plunge my hand and arm into the wort to tighten the spigot, but thankfully I managed to reseal it from the outside and only lost a pint or so.
I switched to 6 gallon better bottles with my next batch, and have been VERY happy with them.
Spigot sanitation is a non-issue, in my opinion. They are easy to dismantle and clean thoroughly. The greater risk is leakage.