Let me first answer the specific questions you are asking and then make a broader comment.
1) If you want to know whether prostitution is forbidden according to Noachide Law, the answer is that it is not. There is a Noahide law that requires society to make rules, so one could argue that if prostitution is illegal in a given country, a prostitute and her/his client would be violating that law, but this is a tangential point.
(BTW, if you want to read up on Noahide laws, there are a number of good books, such as Aaron Lichtenstein’s Seven Laws of Noah and David Novack’s The Image of the Non-Jew in Judaism: The Idea of Noahide Law. There is also a growing community called the Oklahoma B’nai Noah Society, who recently published a ritual guide for prayer and life-cycle events, called Service from the Heart.)
2) If you are worried that it is a Chilul Hashem – no I don’t think that it is. Now, I don’t know what site you are talking about, and you do seem a little sheepish about it (“sort-of stumbled” “such a blog”) so if you mean that it is an “adult website” of sorts, then it might be best not to comment as an Orthodox Jew. Nevertheless, I am not sure even then that it reaches the level of Chilul Hashem if you would comment. A Chilul Hashem generally refers to a Jew behaving in such a way that outsiders will look down on Jews and Judaism. I don’t think trying to articulate your objections to the lifestyle of an escort can be construed as an embarrassment to Judaism, even if it does “give away” that you were surfing on “questionable” sites. There is nothing illegal or immoral per se about reading the “confessions of a escort” even if this might not be the optimal use of your energies from a Torah perspective.
Now I want to take a step back and reflect on what is underlying your question. Why do you want to write this comment? I do not know what brought this woman to her career as a “high class escort” but what is it you want to tell her that she doesn’t already know? Are you going to tell her that the Bible frowns on prostitution? I assume she knows that and has heard it before. Also, it is generally difficult, not to mention somewhat presumptuous, to use your own religious commitments to critique someone who doesn’t share them. Additionally, are you writing because you want to have an effect on her? If so, you should try and think about what would have an effect. Is it because you feel it would be cathartic to speak Torah to her? If that is the reason, she could reasonably counter that you came to her website to satisfy your prurient curiosity and now you feel guilty and are taking it out on her. Is it to counteract the Muslim commenter and offer a different religious response? Not sure if this is valuable, she and other readers may just see the two of you as “the religious fanatics” and miss any nuance.
That said, if you are going to write something, I would suggest hitting on points that most people, irrespective of their religious background, could identify with. (Even if you don’t respond, and I suggest you do not, but it's your call, this may help you think through your message.) Escorts often (though not exclusively) service married men. What are the moral consequences of assisting a man in cheating on his wife? Also, has this behavior contributed to marital friction or divorce? What if he has kids? Now, she can fairly claim that this is his fault and his problem, and I agree, but does she want to be part of that?
Additionally, has she thought about the consequences of this profession on her future? If she wishes to get married and have a family of her own (I have no idea if she does or not) will this hurt her prospects? Will she feel ashamed in front of a future husband/partner or her children? Is she losing precious years of possible companionship in exchange for money and this thrilling but very material lifestyle? Are there dangers involved in this kind of work? (Again, I have no idea, but I can imagine that there could be.) Will this hurt her self-esteem in the long run? Will this hurt her ability to have a fulfilling monogamous sexual relationship in the future? I don’t know the answers to these question but they might be worth pondering.
You could remind her, kindly (and this would distinguish you from the other commenter who chastises her) that she is someone whom people can and do love and who can love others in return. Perhaps this lifestyle, which is very much about her showmanship as an entertainer of sorts, could damage her emotionally or spiritually in a way that will only become apparent later on in life when it cannot be undone.
I am not saying that you should respond or that these thoughts will have an effect or that they are even relevant to her life, but if I were in your situation and felt the need to respond, this would be how I would attempt to offer her another way of thinking about her life and her options without judging her or acting superior.
Answered by: Rabbi Zev Farber