1. What does it mean?
감다살 abbreviates 감 다 살았네, praising someone's feel for what works. A clever edit, a well-timed joke, or a smart choice can earn this reaction, sometimes after the person has seemed off their game.
Also written or said as gamdasal
2. The nuance
It need not mean the person literally lost and recovered a skill. It is a casual assessment of their sense or form, not a general statement that they are alive.
3. Examples
“마지막에 그 음악을 넣다니 편집자 감다살.”
Putting that music at the end was such a good call by the editor.
“오늘 선곡 감다살이네. 분위기랑 딱 맞아.”
Your song choices are on point today. They fit the mood perfectly.
Sources
References support the meaning and usage. Example sentences are written for NoCapWiki.