Student or Learner
What word do we use when we look at someone and also don't look smart ?
If their hair is disordered, they are "ill-kempt" (perhaps only Br Eng) or "dishevelled" .
A useful idiom is 'looking as if they've been dragged through a hedge backwards'. Example: "What's wrong? You look as if you've been dragged through a hedge backwards."
But if you're using smart in the "intelligent" sense, start your thesaurus search from "stupid/thick/dense/slow-witted".