A suffix meaning 'full of' or 'riddled with', typically used for negative things (e.g., 'riddled with mistakes').
彼の答案は間違いだらけだった。
His exam paper was full of mistakes.
部屋はホコリだらけで掃除が必要だ。
The room is covered in dust and needs cleaning.
メールは誤字だらけで読みにくい。
The email is riddled with typos and hard to read.
A suffix meaning 'covered all over with' (blood, mud, etc.), emphasizing that something is coated or soaked with something.
彼は転んで血だらけになった。
He fell and was covered in blood.
子どもの靴は泥だらけだ。
The child's shoes are all covered in mud.
作業着が油だらけになってしまった。
My work clothes got all covered in grease.