A week ago Thursday I went to a dinner put on by Exxon-Mobil, the old school engineer that gave the talk was rabidly against engine flush products, there was almost foam coming out of his mouth when he spoke about them. He graduated from Purdue in '73 though, maybe flush products have changed since then.
Remember, when you do an oil change you only change 80% to 90% of the oil in the engine. If you want to be sure, use the flush product then fill with fresh oil and idle for another 15 minutes, then do your oil change. That should get the flush product down to under 2%.