Had a carboy that had, as it turned out, a crack in it that infected a few (3?) batches very early on (late 80s). Had 1 other that got infected around '92, acetobacter for sure. That's all I can think of on the home level... commercially I had a beer that had pretty high DMS once, that was a mechanical issue; boiler was about to die and I thought I could get one more brew out of it. Unfortunately, I was wrong. Never got a strong boil and the beer suffered. It was a 100% 2row, 1.044 light ale so the DMS was pretty glaring. I got some blackberry extract and threw it in, then blended it with another beer and the result was actually pretty good.