don't know my iq, don't really care to know it either but i do swear
i think the main thing is how you can articulate yourself. the intelligence and swearing part comes in when you can't do anything but swear in order to say what you want. i can say anything i want without swearing.
there really is a right time and a wrong time to swear and use vulgarities in your speech, it really depends on the audience you are addressing. a bunch of academics and high class people you shouldn't swear but with a bunch of blue collar workers, you should pepper in some swear words.
there is no direct correlation between swearing and intelligence but there is some to it, it's just not 100%