Good Black flush "trick" or bad idea?

I can see the benefits of your trick. But fortunately, I have a built-in flush-valve and use it every time I dump the black tank to make sure it's as clean as possible. I even break the law and ....ohhhh, the horror......CLOSE the valve when I am flushing the black tank to let it fill. I have this magical little thing I do...with the water running, I close the valve... count to 120 and then....pull the valve. And all sorts of magical things come forth from that conjuring. After about the fourth or fifth time, the black water runs clear, I turn off the flusher and close the valve. Then, I put in 2 gallons of hot water mixed with Calgon and Dawn through the toilet. No smells and all works good!