It doesn't take much traveling around the world to learn that most people are really bad at communicating with people who don't speak their language. No rocket science there, but it's interesting to see how people's abilities to communicate differ.
First, a broad stereotype - men are much worse than women, and old people are much worse than younger people. Adding these up, older men are the worst, although older women tend to be pretty bad too.
You might ask, "But if you don't speak their language, then how could you possibly communicate?" Well, people who are good communicators follow a number of patterns.
First, they understand how to modulate the speed of their speech. This might sound dumb, but most people are really bad at this. You ask them to please speak slower, and they'll say the first 2-5 syllables slowly, and then revert back to full speed ahead.
Second, they understand that not knowing a word sometimes really just means not knowing a word no matter how many times it's repeated, so they try to explain things with different words. Bad communicators will repeat the exact same thing a few times and then get frustrated. (Bad communicators also make the logical fallacy of thinking that not understanding one thing means not understanding anything, and will vent their frustration about the dumb person on the other end of their conversation in easily understandable words.)
Third, they show a greater degree of verbal flexibility and creativity. They can make the mental leaps from what I'm trying to say to how it should actually be conveyed. Essentially, they can think like someone speaking their language as a non-native. Women are typically said to have better verbal skills than men, so again, no surprise.
Fourth, they're good at charades.
One of the worst communicators I've dealt with recently is a woman who works at the real estate agency that I used to find my apartment. She likes to repeat the same word over and over again as if hearing it a dozen times will somehow make me understand it, even if I've never heard it before. Most conversations result in her making ten phone calls ending with her son (who speaks pretty good English), giving me the phone, and having her son tell me, exasperated, "My mom says everything's fine and you can go." Seriously, that couldn't be communicated? I even asked in proper Korean, "Is everything okay?", and a simple "Ne" escapes her abilities. We can't even communicate on paper, because I can't read her chicken scratch script, and she's unable to write in print.
Ironically, communicating with someone who is too good a communicator can often be bad for your language learning, since they can fall into a pattern of speaking too slowly, too easily, and only using words they know you will understand. If you really want to get good at the language, then you probably need to speak with a lot of bad communicators.