I had your original question in mind when replying.
I find the term “repulsiveness” calls up associations in English that don’t fit with the goal of becoming neutral towards the body - approaching the body with neither craving or aversion.
I know my stance on asubha is strong and can be unpleasant.
The reason is that the body is not a neutral topic, at least not until attachment to it is gone.
This attachment originates in an ingrained view/perspective that the body is attractive, where attractive goes far beyond it’s outside appearances. Asubha practice is to confront this view/perspective by a continuous keeping in mind of the unattractiveness of the body, which will wear down the existing view/perspective.
We might say this is fighting fire with fire - which is also why it’s an unpleasant or “dukkhā based” practice.
Done right there is no point of attachment, just as there is no grabbing a hot piece of coal with bare hands and not burning yourself.
This however is not equanimity, it’s restraint by mindfulness. You might, not being mindful, grasp based on tendency.
This tendency is harder to counter, since instead of paying attention to the mind moving outside, it requires ending the movement of the mind which leads to grasping.
This ending of (the mental movement leading to) grasping is based on the body being hot, not cooling down. The body is hot, the mind knows, and is unwilling to touch it, now or in the future.
Since when not touched there is no pain, this is sufficient to remain equanimous towards the body as it is present.
This does not imply there is no physical pain or discomfort, or pleasure in Jhana (I-IV).
These rise based on the experience of body and cannot be avoided. The mind will however cut all thought processes leading to grasping (the body should be like this, not like that (craving/aversion)).
I recall one sutta where Buddha was experiencing severe pain, and he was said to be “mindfully enduring” it. That’s equanimity towards the body in my understanding.
What I’m wary about is that people consider their practice/understanding right, while there appears to be a fundamental disconnect between the practice and it’s goal.
The goal of asubha practice is not to achieve equanimity towards the body. Disenchantment and dispassion are the natural result when the body is seen with equanimity.
Equanimity is the result of using meditation (leading to immersion) to see the body (and broader: the entire wold/all) as hot (a snare) and the disengaging of the mind as cooling.
This differs from what we in general know as Jhana in that it’s starting point is dukkhā instead of sukhā. It also differs in that the mind won’t cling to it’s starting point in the way it does with sukhā based Jhana.
Perhaps I can approach this different to clarify.
Starting with dukkhā we acknowledge by experience that the world is hot and investigate just that.
Starting with sukhā we eventually find out that sukhā is hot, and investigate just that.
With concentration on the body we find that we can use both dukkhā and sukhā as starting point, where abusha is dukkhā based practice. If there is no dukkhā, it’s not abusha practice.
I think the above might clarify for you as well.
It’s not about “losing interest”, it’s having investigated with full interest and realising how the mind entangles itself with it’s occupations.
You essentially speak about the mind reaching outside (to things seen/heard) and this outflow stopping due to lack of interest/passion. Yet what’s more accurate is that the mind knows it will burn itself when reaching outside, and stops doing that without paying very close attention to it’s whereabouts (and with that stopped entangling itself).
I went to a Thai wat (temple, I think it was Phra That Phanom) once and my wife started walking barefoot on some tiles to walk to a Buddha status which was in full sun, around 14.00.
I followed her, and since no shoes/sandals are allowed I was barefoot as well.
Well, that hurt, but the lighter tiles were a little less hot than the darker ones. So I stepped on those lighter tiles and avoided the darker tiles.
You do that fast, without thinking, once you know you can’t escape the pain entirely.
Something similar, but far deeper, happens in the mind as well once it sees that all there is are lighter and darker shaded tiles to step on in the blistering sun.
And the mind will incline to never step on any of them, since stepping on any of them hurts.
That’s not losing interest nor lack of passion, it’s knowing the nature of these tiles.