I've got $100 says you can't tell the difference between a "flushed" bud and one from a plant that hasn't been. And I've offered this challenge for years and no one has ever been able to tell the difference. Hell, I've had people say I was lying about which was which, because "they" could tell the difference............ yet never were right.
Sorry, but In nature, no, the soil does not become depleted easily unless you plant too much of any one thing in the same space over and over again. Only in a container can that happen quickly. Walk a wild field teaming with life, many many species of plants growing. That soils not depleted, its only our abuse of the soil that depletes it. I grown in organic soil in a greenhouse and I've left plants in the soil till they were stone dead. They didn't deplete the soil, the weather killed them! I've had plants remain green and alive into November, and even survive over night freezing temperatures!
In order for you bud to have no nutrients left in them, you'd have to flush till the buds turn brown and the plant stone dead. As long as they are green, they are alive and have nutrients in them.
Curing is to eliminate the sugars and chlorophyll remaining. If the buds are still green when you cure, I don't care how long you flushed, a proper cure will still take a minimum of 2 weeks.
And I don't understand what you mean by a "clean taste". If buds taste funky, them its a mold or fungus problem, not nutrients, and nothing will fix it! And flushing does not affect how your bud burns, curing does. If you get gooey, black ash, you still have sugars in your buds, and / or, its too moist, that's what causes that, nothing else.
I know its hard to change how you do things, even when you realize that you've been given false information. But science says flushing is a waste of time and diminishes your overall harvest.
I used to be the no flush type. But after a year of my own research and trials, I always flush.. Meaning feeding water only for the last 2-3 weeks. I grow indoors and the objective is to try to mimic nature. In nature, the soil becomes depleated after 4 months or as seasons change.. That is how the plant knows its time is nearing an end. It then uses up all the stored food in the fan leaves as a last ditch effort to rippen before the weather changes. In my grows, it also has an effect on cure time/taste and burn. It seems to me that if you feed as normal up until harvest, it takes a much longer cure to get rid of the chlorophyll type smell and taste. When I flush the cure is fast and clean tasting. I now try to mimic nature as often as possible. And in nature, the soil runs out of food and the plants have to feed on the leaves.
No, you cannot physically remove something a plant as taken in.. But you can most certainly cause the plant to USE any and all EXCESS that has been stored up