Hang on, are you saying that even consensual orgies are disgusting and/or wrong, or are you saying the Romans went in for nonconsensual orgies? How come self-decadence is sinful?

Cause your body is a temple of God's. You are supposed to take care of it. So if say, you go around eating way too much, and throwing up just so you can eat more, that would be a sin. The act of sex isn't wrong, but if that's all you do everyday, if it's your life, then that would be wrong.