Okay, so purpleapple, this is what I'd answer:
Some American (and British, Dutch, etc) men and
women have a period in their life where they sleep with a lot of people, including people they met at a club, on holiday, etc. Usually (though not always) when they're young.
Not all Americans (etc) do that. Not most Americans. But sure, some. And a lot of people (including me) think this is perfectly fine. (As long as people make sure to use condoms etc, and that nothing is done against anyone's will, of course.) There are parts of the country where it's not socially acceptable (among evangelical Christians, for example). There are parts where it totally is.
So the answer is: it depends. It's up to the person. As it should be, really!
But yeah, don't use the word slut for it. It's offensive.