While teachers not looking we'll put this gagh in his tea, and these nanites down Data's back.
There are some real reasons to do with the script, why Wesley was an unlikeable character though. He was never portrayed as a normal teenager with normal teenage problems. I said there were supposed to be other teenagers on board, but where were they, he didn't hang out with them. Instead, he did his homework and was respectful to his mother. He was too smart, and he was allowed to brag about it too much for his own good.