Prince Spinoza, I didn't mean that. I think sex done in a monogamous setting (having a meaningful relationship with total honesty) isn't bad. 
What is it about ploygamy that makes sex bad?
And no, I don't mean only with someone you plan the rest of your life with because for some it isn't realistic. However, I think sex should be had if the relationship is going to be honest. It's just people who have sex constantly and have no idea what the guy has. And not everyone is honest or uses the protection.
Question - a girl sleeps with a different guy everyday. Uses protection each time and ensures all the guys are free from STIs. Is she a slut?