How did you reach this strange conclusion? It seems to me that a person's sexual activities are completely orthogonal to their moral character (excluding non-consensual stuff of course). Sex is a wonderful thing to do with someone, not an awful thing.

Seriously, do you want to marry someone who might cheat because your dick is not as wide as that of a hookup who happened to show up at the college reunion?

What does that have to do with anything? It seems to me that being monogamous has more to do with keeping a promise than not being tempted. I suggest you find someone who will keep their promises in the face of temptation, not someone who won't be tempted at all.

Do you want your teenage daughters to be raised by a woman who dated the football team, and to learn about respecting themselves from such a person?

Some people take the view that sex is fun, and having fun is good for you. Respecting yourself might involve having sex, not repressing your natural desire.

Is sex with a woman special if it used to be available to any guy with a six-pack and a nice car?

Just because a person has a lot of sex doesn't mean they didn't find quality partners.

If a person gets into the habit of casual sex when young, that person's almost certain to cheat in a long-term relationship, even if the relationship is otherwise going well. It's not a habit that people break easily.

Citation needed!