"What if D-O-G really spelled Cat" Dudley Booger Dawson
This post reminded me of one of my favorite jokes:
Q: Did you hear the one about the dyslexic, agnostic, insomniac?
A: He stayed up all night wondering whether or not there really was a doG.
In response to your OP, all my errata'd counters are put in with the rest. Like Paul, I have played the game long enough that I know the correct designations on the most used vehicles, and don't need visually reminded that the T34-M41 with the thick, enclosing square is inaccurate, and the thinner, enclosing square is accurate. Sure, some of the lesser known vehicle errata might catch me in this way, but whoopty-do. If there was an AFV with printed H6, but it was supposed to be H8, I would just retroactively figure that that particular unit didn't get the extra rounds when the Ammo Carrier came by. If, like myself, you do a quick speed-read of the Vehicle Note for each vehicle being used in a particular scenario (with the counters in front of you), you will likely catch 95% of counter errata anyways. Besides, those 'unwanted' counters have also proven useful when playing XL scenarios requiring 10 or 15 of a particular AFV model.