Learning things doesn't make you "smart". Learning how to apply those things does.
Grammar, spelling, and word choice are a few methods we can use to ensure that we are able to communicate with one another in a printed medium. Casual use of such neologisms as "I was all like" or using numbers to represent phonemes ("sk8", "4vr", etc.) betray either laziness, ignorance, or a rather cavalier attitude toward the idea of being understood (which begs the question - if you don't care whether people can comprehend what you've written, why did you write?).
Since everyone in the United States, at least, is exposed to the concept of correct spelling (attendance of some form of education is mandatory in every state), "ignorance" is no longer an excuse. However, if one declines to attempt to apply said rules of spelling to one's own communications, this does seem to be an indicator that one lacks the intelligence to do so.
_________________
Sodium is a metal that reacts explosively when exposed to water. Chlorine is a gas that'll kill you dead in moments. Together they make my fries taste good.