Natural,
All you can do is try to be culturally sensitive. It really is a minefield - not just in speech, but actions and body language too. As a traveler, things we take for granted can be highly offensive to other cultures.
On the flipside, people in other cultures ought to be sensitive that not everyone from other cultures are aware of their cultural norms and expectations. An example would be knowing and observing the religious principles in Arab countries because those are expected of visitors, but certain hand gestures can have varied meanings in some countries where you may accidentally offend. Ignoring the former may land you in prison, the second might just require some fast talking/explanation.

Of course, some people are reasonable and realize that no slight is intended. Others, as we know are not. In these situations, the context of your communication is all that you can point to. I've had some close calls in my travels!
I never even associated niggardly with the racial slur, despite the visual similarities. It would be hard to mix up the context of this word in post as they have vastly different meanings.
We just have to be more aware when we leave our fair island bro.