Some people don't think of me as very blunt, but I know I can be. This is especially true with family, and close friends, though the motivations are more out of respect for them to tell them the truth moreso than the sort of bluntness I do with strangers.
With strangers: A classic case of my blunt mouth coming out is a recent conversation with an advisor I had at my school that had caused a huge fuss already.. She nonchalantly tells me, "Did you send the email?" 'What email?' "The email with your student ID, name, and that you need to be certified." 'I've never heard of this before.. could you help me?' (I asked this because she never actually gave me an address to email it to.) To which she replies, "Well, you can do this yourself anytime.." And I stand up and just say loud enough for the cubicles next to us to hear, 'If you're that reluctant to help me, just SAY so and I'll ask someone else for this information and their assistance ma'am.' She straightens up, and says, "No no, I can help you this time, here is the address..." ..
Classic example around family: I was having another talk with my youngest sister about how she talks and treats her mother, and how that's affecting her mother. She starts to cry and I ask what is making her cry, and she states, "When you say things like that you make me sound like a bad person!" and I reply, "I'm only telling you what I've seen you do. If those actions make you a bad person, you should be happy that you're finally realizing that they're bad, so you can correct them.. and then you won't have a reason to cry anymore." .... To me, I was being compassionate by opening her eyes to things from people outside of herself.. to her, I was being crude and brutal when it wasn't necessary to do so..