You can read The Master Cleanse online, that has the protocols for the salt flush.
When I was super sick 5 years ago, if I did the salt flush, I don't think it would have come out. (I was constipated my whole life! My PH was 4.8 back then).
But now, when I do MC, I usually do 2 or 3 salt flushes a day.
My colon is very clean because of my diet and good bacteria. And yet I will pass junk from my colon up to day 5, during MC. It shows how many areas poo can hide haha.