What is a good sex?
i think the only logical definition of it is when you and your partner are into the session and both of you fuck each other's brain out.
When one party is interested while the other just going through the motion.
Very bad sex?
When both parties just going through the motion.
I would rather not have sex if it is not good. No point.
Shit, why do you have sex if you are just going through the motion?