I always thought the Humperdinck episode highlighted one of my less favorite tropes in sci-fi: that the first person we see of a given race creates the template that all other members of the race must follow.
The idea of the entire El-Aurian species being "a race of listeners," as Odo put it, always came across pretty poorly to me. Granted, they didn't lean too heavily on that for his characterization, but it rubbed me wrong that this "racially enlightened series" still reduced a whole race to a single quality that Guinan happened to be strong in.