I speak softly and carry a big vocabulary, so yes, I often find myself misunderstood. In a crowded or noisy situation, people frequently are unable to hear what I say, so they hear what they want to hear and assume that that is what I have said. If someone asks me to repeat myself or speak louder, it usually does little good, as in certain moods and/or situations I am constitutionally unable to raise my voice. Piss me off and I'll make your ears bleed, but otherwise I'm a church mouse.
Also, I tend to use big four-dollar words and archaic expressions, which, along with my dry, dark, and sometimes even morbid sense of humor, are apt to confuse the bejesus out of anyone who actually manages to hear what I say. Some people understand me just fine—I think they build up a tolerance with exposure—but others, perhaps most, seem baffled, especially younger folks and those with less educated or more pedestrian minds.