Associating swearing or any kind of informal language with unintelligence is pretty biased, and I’d like to encourage you to reflect on where those associations come from for you, and if they are fair or substantial. All kinds of people swear, for all kinds of reasons; I swear in my writing for emphasis, and because it reflects the way I speak to friends and loved ones. It’s the way people around me spoke growing up. It is not unintelligent or unusual; the use of these words is very culturally and economically rooted.