Yeughh, I'm sorry, it's the absolute worst. I begudgingly understand if you need to fly when you're sick, after all - what if you get sick while on vacation? Most people can't just not go to work for an additional 2 weeks while you recover, and buy a hotel room for that long. At the very least though get a mask and just keep it contained.
Sure I have an immune system, it doesn't mean I want to use it when I'm going on vacation!