Do you mean the raw studly irresistable to ladies kind of "appeal"? If that's what you mean, I can't answer that since I'm not gay.
If you mean likeability then his looks mean nothing to me.
After he masked himself, he still made himself quite endearing to people as the Magic Condorman - Shen Diao Da Xia (or just Xia as YG prefers). GX developed a crush on him before she saw his face. YG's appeal is that he is who he is.