1. What does it mean?
셀기꾼 blends 셀카, selfie, with 사기꾼, swindler. It suggests that angles, lighting, filters, or editing make a person's selfies look markedly different from their everyday appearance. People sometimes apply it jokingly to themselves.
Also written or said as selgikkun
2. The nuance
It can be appearance-shaming when aimed at someone else. The word does not establish actual deception or fraud, and a flattering photograph alone proves neither.
3. Examples
“조명 잘 받은 사진을 보고 내가 셀기꾼이네 하고 웃었어.”
I joked that I was a 'selfie fraud' after seeing how flattering the lighting was.
“남의 사진에 셀기꾼이라고 댓글 다는 건 무례해.”
Calling someone a 'selfie fraud' under their photo is rude.
Sources
References support the meaning and usage. Example sentences are written for NoCapWiki.