As someone who actually trains roosters, that's just not true. I have many roosters who have never gone back to their old behavior.
Much of Pavlov has been discredited - that's not an appropriate model to use for understanding rooster behavior.
I would say that "good" and "bad" also describes the way people are talking on this forum. Many are using the word "bad," and the entire concept that an aggressive rooster can never change his behavior suggests he is born "bad" and is therefore irredeemable, and unworthy of empathy. Because if he can't change, why even try to understand his point of view?"mean" and "nice" describe the behavior in a way that everyone understands. it is same for "aggressive" and "docile".
Please, tell us about it. All the accounts I have seen make me think the best-possible outcome is that the caretakers learn to avoid certain triggers and requires lifelong training. If you know how to permanently change a rooster, please tell us about it. You won't believe me, but I am a huge rooster advocate in my neighborhood and I have taken my rooster to the park and other social places to show people how "nice" a nice rooster can be.
I do believe you and I thank you for responding with curiosity.
It will take me a bit to craft this response, but first could you help me understand your position better? Do you believe that all chickens are only capable of responding to stimuli through positive and negative reinforcement, and aren't capable of anything else? Or do you think they're capable of more social behavior, like bonding with you? Could you have a sort of friendship with a chicken? Or do you think they're just automatons?
I want to make sure my response is targeted toward your way of thinking, otherwise it won't mean anything to you.