1. What does it mean?
도배 literally means wallpapering. Online, the metaphor is covering a board or chat with so much similar content that it dominates what everyone can see.
Also written or said as dobae
2. The nuance
One long, relevant explanation is not necessarily 도배. It usually criticizes repetition or volume that disrupts the space, but can also exaggerate how often a harmless topic appears.
3. Examples
“같은 질문을 계속 도배하면 다른 글이 묻혀.”
Repeating the same question floods the board and buries other posts.
“단톡이 고양이 사진으로 도배돼서 한참 웃었어.”
The group chat was flooded with cat photos, and I laughed for ages.
Sources
References support the meaning and usage. Example sentences are written for NoCapWiki.