This is the 2327th most frequent Japanese word.
だらけ
Full of; covered with; riddled with.
In this sentence, 'だらけ' is used to describe the room as being entirely covered or filled with trash (ゴミ), signifying an excessive presence.
部屋がゴミだらけだ。
The room is full of trash.
Here, 'だらけ' is applied to indicate that the textbook contains numerous errors (間違い), implying a negative abundance.
教科書は間違いだらけです。
The textbook is full of errors.
In this example, 'だらけ' is used to describe the story as being full of contradictions (矛盾), portraying a situation densely composed of something undesirable.