Hot damn, I can cross diacetyl off the list of things I might not be able to recognize in a beer. I pulled a sample from a brown ale I just brewed on Sunday and whiffed/tasted the most distinct butterscotch. I hope assume the yeast will to go town in the next week or so and clear it all up. I never, ever open a fermenter before the two week mark, but I thought I'd give it a shot this time to see how effective my starter was with respect to gravity after 3 days. Now I guess I'm stuck trying to cross other stuff off the list, such as determining whether the beer is oxidized/contaminated/full of tannins/etc.