As Nicholas said in response to the other question, there are questions to be asked about what is appropriate and inappropriate behavior in the workplace. And, while there are companies that prohibit co-workers from dating, most do not, which is simply to say that sexual harassment policies are not in general intended to prohibit all sexual interaction between co-workers, but only such interaction as, first, is unwelcome or unwanted and, second, constitutes a form of harassment.
Even unwelcome sexual attention, by itself, does not constitute harassment, according to the definition promulgated by the Equal Employment Opportunity Commission, but only if:
- submission to such conduct is made either explicitly or implicitly a term or condition of an individual's employment,
- submission to or rejection of such conduct by an individual is used as the basis for employment decisions affecting such individuals, or
- such conduct has the purpose or effect of unreasonably interfering with an individual's work performance or creating an intimidating, hostile, or offensive working environment.
The first two conditions are kind of obvious. It is the last condition that can be harder to evaluate, in practice.
Asking someone out on a date, for example, all by itself, certainly would not constitute harassment under this definition. Indeed, as I understand it, merely asking someone out does not constitute an expression of "sexual interest", but of romantic interest, which is different. That said, the line here is blurry, and if the person doing the asking is in a position of authority over the other person, then we are on dangerous ground, since then condition (1) or (2) may be met. And repeatedly asking someone out could constitute harassment, as could asking every woman in the company out, since it is easy to see how condition (3) could be met in such a case.
Telling someone flat out that you'd love to get them in the sack is something else entirely. Most people would not receive such a remark as a compliment, for the simple reason that such a remark, made outside an appropriate sort of context or relationship, does not express any real appreciation for the other person, but only how that person might be used to satisfy one's own selfish desires. People rightly feel "objectified" by such comments and, as a result, self-conscious and otherwise uncomfortable, and that is why making such remarks can easily satisfy condition (3). That said, however, a single such remark probably does not constitute harassment, but a pattern of making such remarks very likely would.
That said, companies have a right and duty to ensure that the workplace is free of intimidation, and they also have an interest in protecting themselves from litigation. So a company might have rules that prohibit the making of such remarks, for example, even though making one such remark might not constitute harassment. Such rules are perfectly understandable, seen from this point of view.