Believe it or not there are not a lot of characters in cartoons, comics, anime, and etc. that wear glasses (which is not nessesarly a bad thing because you know not everyone is blind), but when a glasses character is introduced into the main cast they are usually given the role of smart guy, brains, sane man, or really any role that shows off their intelligence.
But every once it a while you get a glasses character that doesn't fill the smart guy role... Hell he could even be a dumbass! Media today has the myth glasses=smart that when we're given a glasses character who well... doesn't live up to the stereotype it can be surprising and entertaining.
Jimmy Neutron-Carl Wheezer: Lampshaded in an episode, and made obvious in the episodes "Journey to the Center of Carl." and "I Dream of Jimmy.". Well actually let's just say it's made obvious throught the entire series, increasingly so.
Daily Lives of High School Boys-Hidenori Tabata: Dear lord is he crazy but in the best way! From doing a live dating sim. for his best friend to stealing said friend's sister's bra he is not even close to being the smart guy from the group.
Daily Lives of High School Boys/ High School Girls are Funky-Yanagin: Pretty much the female version of Hidenori Tabata and just as awesomely crazy. While it is proven that she is book smart, 2nd in her class to only another glasses character, she definitely does NOT use her knowledge to her advantage. She is even considered worse than her male counter part with her constant harrasment to any male character.
- Ano Hana :There's Anjou (Anaru) who actually has glasses but is explicitly stated to be an extremely slow learner and isn't the brightest of the lot.Though The Smart Glasses are played straight by Tsuruko.
-Kimihiro Watanuki: While he's probably an average on the intelligence scale but compared to his mystic employer, Yuko, and his constant savior, Doumeki, he's just a spazzing man with glasses.