Was it 'Political Correctness' that changed Liz and Sally.
In the original comic book by Stan Lee and Steve Ditko Liz Allen was a blonde and her best friend Sally Avril was a brunette and possibly Latin.
Liz starts off as stuck up and rude to Peter but comes around eventually while Sally remains incorrigible.
In the TV series its the same pattern except Liz and Sally are ethnically reversed.
Was it to be 'PC' and not offend the Latin viewers by making the girl who wises up be the Latin and make the incorrigible one an easily targeted blonde?