I think that one of the worst aspects of being aro is when you get asked out or someone flirts with you. If you just say "no" as your excuse, they keep trying because that "no" is obviously a "yes" somehow in their head. If you are comfortable coming out to them (even if you don't know them that well) and say that you are aro, they are not going to take you seriously. Maybe it's also because they ignore you and keep trying for whatever reason, but sometimes it's because people are not aware that aromanticism is a thing just because they are romantics and don't believe that there are people who are not. I think this is one of the rudest things you can do, not taking seriously someone's identity just because it's not the same as yours and therefore that person is confused or lying or crazy.
I don't know this is a random thought and it's so obvious but I wanted to share it anyway.