never tried. some of those german beers have very little carbonation though. I bought a case of something that was over carbonated and I thought about trying to return it. I never did though.
If I had a bad 1/8 or more; especially something nice like a storm king, I'd definitely return it. VBC is 5 mins from my house, so I buy a lot of beer direct from them and have never had a problem.
Edit: Just re-read your post. sounds like you've had the german beer before and know what it's supposed to be like. I replied under the assumption that you picked it up as a novelty item - which is usually the case if I have a mini keg.
I'd return that isht.