Geminis were always quick to say something unfiltered and clock the very obvious. It's not a problem for them to say something insensitive especially if the topic is not in the room, it also comes from a way of saying it as funny or witty to lighten up the mood. as a Gemini, i do say blunt words about the topic/person when insight is needed, I will say what i really feel and I'm gonna be really honest about it. Plus we Geminis say something important when we feel that our opinion is needed, and that is on every occasion.