Sooo, what is “Good sex...” compared to just “Sex”???
Maybe it lies in the eye of the beholder. “Fox example, the worst sex I ever had was vunderful!”
Indeed “good sex” is in the eye of the beholder. If a man will slowly deliver many multiple orgasms to his wife before satisfying himself, she will probably consider that “good”; and if a woman will do all the things that will excite her husband before bringing him to climax, he will probably consider that “good”.
Good sex is the result of effort and caring for the needs of the partner ahead of your own needs. In this way both partners will want to be back for more as often as possible and will never stray.