Hi Khalil,
The Buddha did not offer the same advice to monastics and to householders on sex. The Buddha knew that if the householders were celibate and not engaged in "out in the world" commercial and other activities, the Sangha (and the whole human race!) would disappear in a generation and their would be no means of economic support of the Sangha.
Also, Indian (so called "Hinayana" Small Vehicle) South Asian Buddhism had an emphasis on rejection and suppression of emotions, disgust with the world and withdrawal from daily life, and rejection of the body and its natural functions (including sexual urges) that transformed as Buddhism came north into China, and especially into Japan.
As I spoke about in my "Ango" Talk this week, monastics (for obvious reasons) have had a tendency through the centuries to say that monasticism is the only real place of practice. They obviously have reasons to say that, living that lifestyle themselves. However, the historical Buddha never said that (he said the practice out in the world was the harder practice, not impossible), and Zen folks and Mahayana Buddhism in general have always emphasized the possibilities for liberation "out in the world."
In China, with the Mahayana, there was a greater emphasis on transcending and balancing the human desires and emotions rather than rejection and complete cooling (although monastics continue to be celibate), more earthiness and acceptance of this life and the world. In Japan, it became even more so, with priests now overwhelmingly married with kids (with the emphasis now on wholesome, healthy relationships), and Zen's emphasis on realization in this life and in this world. The body is not to be rejected, but honored and treated well. Tibetans also seem to have very mixed attitudes toward sex, sometimes rejecting and sometimes accepting.
So, no, there is no particular practice recommended of sitting, contemplating how loathsome is the body. The body is our temple, to be respected and handled with care. The one exception is, I would think, if someone had a problem of excess such as a sex or porno addiction. In that case, with the lack of balance, excess and other unhealthful aspects, we might encourage someone to think about how loathsome the body is as a counter-measure (besides recommending that they seek psychological counseling for the mental issues involved). When young trainees are in the monastery (usually for only a period of a few months to a couple of years), they are expected to be celibate (in theory). Like boot camp in the military, it is cold shower time. However, outside the monastery, priests date and marry.
The question of porno is difficult, and my Dharma Bro. Brad Warner has written about it sometimes with former porn actress (and daughter of the late noted Zen Teachers from the San Francisco Zen Center, Blanche and Lou Hartman, where she was raised) Nina Hartley
https://www.suicidegirls.com/girls/e.../nina-hartley/
The point Nina (who was apparently a porn actress for many years) and Brad make is that being a "sex worker" is a voluntary choice for many in the industry, and not always a situation of abuse and economic oppression as many describe. In many countries outside the US, prostitution is more accepted and often regulated. I do not know if I accept these arguments myself. I recently watched two documentaries called "After Porn" of interviews with former actors and actresses in the adult film business, and they seem to have very mixed feelings about what they did, not negative for many. However, I tend to think that the situation is not so clear for less "elite" people in the industry (and even for many of them), especially at the lower ends of the sex industry. Prostitution, the world's oldest profession, existed in Buddha's day, Dogen's day and exists in modern Asia (Thailand, for example, one of the world's most Buddhist countries, is also a country with a very open sex industry). In some of the old Suttas, Buddha seems to accept financial support from working concubines and such, while accepting their profession without particular moral judgment.
http://www.palikanon.com/english/pal...ambapaalii.htm
Chinese Master Shengyen touches on this in footnote 6 here ...
https://books.google.co.jp/books?id=...0sutta&f=false
My own feeling is that, while human sexual need is not to be rejected, it must be handled like fire (good for light and cooking when properly handled, but easy to burn one if out of control). I believe that some sex workers may be there by choice and free will, and not find their profession abusive, but perhaps the vast majority are subject to abuse, violence, human trafficking, drugs and other addictions and the like, and that is wrong.
Gassho, J
SatToday