There are great stories here and I mean not to discount anyone's progression, but part of being awake and a free thinker is considering the possibility that there is much further to go.
I don't see much in the way of a methodology for knowing you are brainwashed. I think the realization comes when you shed a belief you once held to be true when you finally discern that it's not. Perhaps, we see others still unable to reconcile certain incompatible perceptions of truth and think, by comparison, that we must no longer be brainwashed. That's probably true, but I never remember feeling brainwashed in the first place. It was more like just being unaware and and a bit unwilling to confront things.
So, this begs the question, "How much are we still brainwashed?"
As an example, since I've come to the DP, I've been confronted with competing conceptions about many things I failed to even question about Woodrow Wilson, "Honest" Abe and the expansion of the federal government (even through Kennedy), perceptions of Democracy vs. a Constitutional Republic, how Regan played the fall of the Soviets as a victory in the cold war, and a plethora of other accounts of historical events (many current) and the motivations for slanting their facts.
So, I've come to realize that shedding your load of brainwashing is not an all or nothing endeavor. It's a continuing process and, to some extent, I must still be brainwashed.