Exactly what "era" of the comic books portrayed Joker as dancing around a lot, acting primarily juvenile, and laughing profusely? TV shows don't count.
How exactly do you know Ledger's Joker is or isn't permanently white? Yes, Ledger's Joker DOES wear make-up, but he has NO explanation and NO origin, so unlike Batman 89', there is no explanation either way for Joker's appearance. Also, as I stated earlier, appearance is not the issue here, but characterization is.
Also to correct you, in the very first comic appearance Joker DID put on makeup. It was not clown makeup, but it was skin-tone makeup to disguise himself as a cop. Furthermore, in his first appearance Joker's white appearance was never explained, just like Joker's appearance in The Dark Knight is never explained. For all we know, Joker's white skin in his first comic appearance WAS makeup.
Yes, the characters do evolve BUT there are some key elements that consistently remain throughout the ages.
Please tell me exactly what aspects of Heath Joker's characterization contradicts what I am saying?
While you might not care what is definitive and what isn't, the vast majority of Batman fans collectively have ONE definitive Joker in their minds. The definitive portrayal of the Joker varies among a minority of Batman fans. By the way, definitive means fully formed and complete.
I don't care what your opinion is on a definitive portrayal, but Nicholson's Joker was NOT a definitive or comically accurate portrayal in terms of characterization for the vast majority of Batman fans. Heath's portrayal IS a definitive portrayal for the vast majority of Batman fans. THAT is the difference. Nicholson's portrayal of the Joker was not fully formed, nor was it complete. The characterization of Nicholson's Joker was missing some major aspects for it to be considered fully formed, complete and therefore definitive.
Please don't rehash any appearance arguments as I am specifically focusing on characterization here.