When we want to say that something is covered in or full of something else (e.g. “the bookshelf is covered in dust”, “the room is full of rubbish”, “the report is full of mistakes”) we use the phrase だらけ. It attaches directly to nouns and modifies other nouns with the possessive particle, giving us two structures:
【Noun】だらけ
【Noun】だらけの【Noun】
部屋はゴミだらけ。
The room is full of rubbish.
１ヶ月も掃除していなくて、家はほこりだらけだよ。
I didn’t clean for a month and the house is covered in dust.
自転車から転んじゃって体は傷だらけ。
I fell off my bike and I’m covered in scratches/injuries.
だらけ can also be used in an abstract sense.
私は悩みだらけだよ。
I’m full of worries.
間違いだらけのレポートです。
A report full of mistakes.
But the connotation must be negative (or at least not positive).
懇親会は友達だらけで楽しかった。(✘)
[The social event was full of my friends—it was fun.]
Instead, it would be much more natural to just say:
懇親会に友達がたくさんいて楽しかった。
The social event had lots of my friends—it was fun.
渋谷は人だらけで動けなかった。
I couldn’t move for all the people in Shibuya.
Since the negative connotation isn’t placed on “people” per se, but rather the fact that they were in your way and causing a nuisance, the above is acceptable.
だらけ vs. ばかり
So what’s the difference? Both phrases can have a negative connotation, and both can be used to say there is a lot of something.
The most important distinction is that だらけ refers to a surface or space being covered in or littered with many undesirable things (like dust, scratches, or mistakes). ばかり, on the other hand, suggests exclusivity—that there is nothing but one specific thing out of many possibilities.
怪我して体が傷だらけだった。
I had an accident and my body was covered in bruises/scratches.
怪我して体が傷ばかりだった。(✘)
(Sounds unnatural—this implies your body is made of “nothing but” scratches, or out of all the things you could be covered in, you exclusively chose scratches).
When to use ばかり
To see how ばかり actually works, look at how it expresses exclusivity (doing “nothing but” an action, or a group consisting of “only” one type of thing).
彼は文句ばかり言っている。
He does nothing but complain.
For a direct comparison with nouns, think about a test with a bad score:
間違いだらけのテスト: A test littered with mistakes (there are correct answers, but there is a lot of red ink covering the page).
間違いばかりのテスト: A test of nothing but mistakes (almost every single answer is wrong; it consists exclusively of errors).
まみれ (Smeared / Covered in)
まみれ is the better choice when you want to say that a surface is smeared or physically coated in liquids or fine dirt (e.g., blood, sweat, mud, oil).
涙まみれの顔。
A face covered in tears.
血まみれの人。
Someone covered in blood.
石油まみれの水鳥を救う。
Rescue a bird covered in oil.
泥まみれになって遊ぶ。
To get covered in mud and play.
ずくめ (Entirely / Succession of)
Whereas the usage of だらけ and まみれ can overlap somewhat, ずくめ is unique. Physically, it is normally used for colours (which sounds unnatural with either of the other two expressions).
黒ずくめの男性。
A man entirely dressed in black.
白ずくめの服装をする。
To dress completely in white.
Crucial JLPT Rule: On exams, ずくめ is frequently tested in its abstract form. It is used to express a continuous succession of events or things (e.g., “a year full of good things” or “a record full of nothing but rules”). Unlike だらけ, it can be used for positive things.
今年は結婚もしたし、昇進もしたし、いいことずくめだった。
I got married and promoted this year; it was a year full of (nothing but) good things.