Here's a couple of thoughts.
What was the average number of flight hours (i.e., experience) the German pilots had versus the Allies? By the time the US entered the European war with significant fighters the Germans had already been fighting for years. Also, at some point most of the US pilots went home, something that wasn't really an option for the Luftwaffe (except leave) so the average level of US experience was probably much lower...maybe the US never learned the lesson. Ever hear the one about no old, bold pilots?
As far as any success the US had using this tactic we see it all the time in AH. If one pilot tried to avoid the HO and the other doesn't that means the guy pressing the HO has the advantage both in forcing the other pilot to maneuver to defeat the HO (eliminating the possibility of a mutual HO) and he's defending, not maneuvering for advantage. So, even if the HO is unsuccessful, the HO'er usually gains an advantage. Not surprising that the guy not following the "rules" wins (vulching, picking, hoing, etc.) Of course, it sounds reasonable that the Germans learned the lesson of the HO in large part to the simple mathematics of 100 50Cals coming at him vs 10 20mm going out, the odds were just not with him. And BTW, anyone see what a 50cal does to a body? It's really irrelevant whether the round is a 20mm or 50cal when it comes to soft targets...they both dismember it although the 20mm might be a bit more "colorful".
Mace