This might not always be the case, not even in the same anime and whether if said character’s blond or brown’s up to the viewer’s guess. But it’s parsimonious to think that many, if not most, light-haired anime characters (grey/white, light brown, blond) are othered in a way their counterparts in non-Japanese/non-African/non-Asian media aren’t. A few of them are daft but they’re much likelier to be shady, exceptional, uncanny or striking in some manner.
A good number of those haughty, aloof or even fiery anime females are blond. (Kind or at least tolerable blondes do exist in anime.) As are the more magical, feral or otherworldly ones even if this isn’t always the case not even in the same story. This might be my opinion but it’s parsimonious to assume that if a blond character shows up in anime and even in non-Japanese African and Asian media, they’re going to be exceptional in some way.
Some of them could really be smart (as in Great Teacher Onizuka and Pokemon), worldly (Glass Mask, Sailor Moon and its prequel to some extent), shady characters (GTO, Jojo’s Bizarre Adventures, Neon Genesis Evangelion, Pokemon), otherworldly (Jojo’s Bizarre Adventures again, Sailor Moon too, Inuyasha, Devil May Cry) and/or merely exceptional. I even think this might be coloured by other things.
Whether if it’s students sometimes not complying with school rules by bleaching their hair, certain delinquents/subcultures (see also Death Note’s Misa), albinos (who’re often bullied), glamourous celebrities with bleached hair or foreigners blond and light hair in general’s going to be othered in a way they aren’t in Western media.