Once upon a time, I worked with the worst communicator I have ever met. She constantly misunderstood things other people said, and in turn said things that weren’t what she really meant. It was very confusing!
I hope you haven’t encountered someone like that in your work, but in case you have or do in the future, here’s what I learned the hard way.
Often, poor communicators are simply poor speakers and listeners. This means that you can clarify things with them in writing, which may vastly simplify your life. Start by following up after any conversations with a recap. If the person is your equal or subordinate, restate what you said in the conversation and what you understood the other person to have said. If the person is your supervisor or manager, say something like, “My understanding of what you said was….” Then ask for clarification if you understand incorrectly: “If this is not the case, please correct me by tomorrow. Otherwise, I will proceed with [Project A].” This gives the other person 24 hours to respond, but even more importantly, it gives you backup in case the poor communicator complains about you. (In my experience, they are the first people to point the finger, for exactly their own shortcomings.)
However, if you work with someone who doesn’t read or processes written information differently, you’ll need to rethink you how speak to that person. In that case, you’ll want to bookend your main points with a signal that those are the main points: “Okay, so to be clear, you want me to do A, B, and C, using resource X, by deadline Y. Is that a fair description?” This will feel tiresome at the beginning, but once you get into the habit, it will let you keep your sanity.
In the worst possible situations, you may need to do both. I know that this can feel very unfair if you aren’t the poor communicator. And it does mean more work for you, but I promise, it will save you grief in the long run.