ずくめ

ずくめ goes straight after a noun and means "nothing but": everything about the thing, or everything in a stretch of time, is that one noun. The result works like a noun, taking の before another noun and だ or で at the end of a clause.

Which nouns take it

ずくめ goes with a small set of nouns, and you learn them as phrases. A colour means dressed in it from head to foot – くろずくめ黒ずくめ and しろ白ずくめ are the ones you meet. With いいこと, めでたいこと, ごちそう, きそく規則 or いれい異例, it means one after another, with nothing else in between.

ずくめ or だらけ

だらけ is "covered in", "full of", and what it is full of is usually unwelcome: mud, mistakes, rubbish. ずくめ is about the whole thing being one kind, and the thing can be good or bad. まみれ is narrower still – smeared with something wet or dirty, like blood or sweat.