I should be careful with my language here, but I have to say I often feel Koreans accept things that seem ridiculous to visitors to the country. Starting with an admittedly trivial subject, they lap up horrible stereotypes about Native speaker ESL teachers. More seriously, their opinions regarding the American military presence are easily swayed and they do not appear to want to test the things the media tells them. As a final example, did anyone question Dr Hwang Woo-suk's results?
I cannot say this is the reason, the cause, but it must be related in some way: dictionaries in Korea are missing some useful vocabulary.
Consider these pictures (The first is from Co-build, from the Bank of England):
Now a Korean-English dictionary.
All are missing 'gullible'. Even the Korean term ,"속다" is missing (and that word was dang hard to find to see if it was missing). I have started a petition on Facebook and, for those not so interested in Facebook, here is another petition site. Remember, we cannot teach critical thinking to Koreans until they understand what it means to be gullible.