Sometimes I do readily want to offend others. I don't think being Fi base means you'll always be rainbows and sunshine, it just means you pay attention to and understand what you could say to offend or not offend others. That's sort of an upper-hand in communication, I think, in some ways. Anyway, sometimes I say shit for the sole purpose of pissing people off and I might do it because I don't like them, or I think the things they say are dumb.

My candid use of language is often speckled with colourful metaphors involving sexual acts and/or genitalia, but I'm wary of whom I'm speaking to and I wouldn't do it in front of people get hung up on certain words, or flinch at the graphic imagery. It doesn't mean I like it that way, though, I'm never comfortable with those people and we'd never go past being formal. I'm comfortable around people who are okay with me swearing my head off.

I know INFjs who would never swear though, and while they look adorable and meek and harmless, they have an undercurrent of bigotry and hatred for people not doing things the "right way", having this judgmental streak against people who don't love humanity the right way or who laugh at dark humour and so forth. I think, among many other things, this is one of the biggest weaknesses native to INFjs.

Out of the ones I know, there are IXFjs who are cool with pretty much everything but they don't swear themselves or don't prefer that sort of language, though they aren't pedantic about it. I know another INFj who swears as much as I do, but it's more ironic and not-really-taking-oneself-seriously kind of way. I don't know any INFjs who would dump swear words without consideration, though, there's always a testing period where they try to get a feel for what the other person is like before opening up. IME, anyway.