I would probably still read their books if they were a contemporary author, although it does depend on the genre.
I would certainly still read their books if they were from a different era, as Cariadagain said earlier, it's so difficult to make judgements about past values.
Enid Blyton would probably be just as unpleasant if she was contemporary though - but attitudes to women /men, race, hunting etc have changed so much I cannot blame past authors for not being as enlightened as we now think ourselves (the enlightenment probably still has a way to go yet).