It's innate....we're drawn to people/things that are attractive. Associating ugly with evil is drilled into us from a young age. Take a look at the fairy tales, for example....the evil witch is usually ugly. Yes, in the real world, there ARE attractive people that are evil. But it's interesting that literature for children doesn't take that into account.....it's something you learn...through your experiences..as you go through life.
dunno.. times are changing mate
if u have seen some old movies like MacBeth and other classics... u will see that "attractive" people are the evil ones..
heck, even in teen movies you see the pretty blondie girl being the evil rat... so we end up thinking that all the pretty girls at school are evil... yet they may be very sweet inside..
i think its all ridicilous.