I am a relatively new BJCP judge, and have judged about a half dozen competitions. I have had a few instances where I have perceived DMS when the other judges haven't.
We recently carbed up 3 versions of a 1.080 or so RIS (naked, oak-aged, bourbon oak aged) and I perceive DMS in all of them, particularly when its served on the cold side. Once its warmed a bit, I get an amazing symphony of bready malt, baker's chocolate, light roast, warming, and some hop flavor.
I honestly have no idea how this beer could have had DMS. 100 minute boil, in-line therminator, cold pitched US-05, fermented at 66, temp raised to 68 after a week, then 70 for the remainder. We used magnum to bitter to about 40 IBU, then got the remaining IBU's (total of 80, calculated) from Green Bullet hops, which I'm told are somewhat like Fuggles or EKG, especially when used late. I am confident in our cleanliness, hot and cold-side processes. We ferment in a 1/2 bbl stainless steel conical, in a dual-stage temp controlled fridge.
Any feedback or similar experiences would be appreciated!