You can still have consent and still be immoral is what she is saying. The other party might not know fully what kind of harm they are getting themselves into, but the person who is knowingly causing the harm would be the person in the wrong morally anyways. It depends on what is known going into the situation and if the whole thing is built upon lies or not.
Immorality is one thing, I wouldn't attach the word whore to being exclusively immoral. It is all about money. If you are in a place where exchanging cash for sex is perfectly acceptable morally, then calling someone a whore isn't such a big deal probably. A slut enjoys sex for what enjoyment they get out of it, they have sex because they love it. A nympho is addicted, but really doesn't gain much pleasure if any at all from sex. Monogamy has nothing to do with any of those imo. Someone can be a whore, slut or nympho and still be monogamous imo. We do practice what is called serial monogamy these days. It is possible to be all 3.... slut, nympho and whore.