Can I tell my boss not to hire someone full time because he smells?
Does he really smell that bad?
He is a total nightmare, he has severe hygiene problems.
It is okay to be concerned about your work environment but you cannot tell your boss who to hire. It will upset him and cause you to be reprimanded.
I'm sick and tired of this person.
You're not in charge of who your boss hires, and you'll have to be respectful of who he hires. While it might be annoying, it just is not your place.