Not only can people Judge by the way we look but they can also judge by the way we Speak. Africa has many different countries with many different languages which means people speak in many different accents. Because I am Zimbabwean but moved to New Zealand young and then moved to Australia my accent is mixed and diverse and every time I speak I always get asked "Where is that accent from?" or "Your English is great" or even "You don't sound African?".
This has happened to me before as well but I was at work and as soon as I spoke the "professional" man stops me and says "I love your accent what is that?". Really? Then when I passed the comment off by saying Thank you and kept talking, he goes and tries to mimic me, like seriously? You have an accent too but do you see me standing there and going "Good daaay Maate."
The thing is though, yes, some Westerners do this but some Africans tend to judge you if you don't speak the way they speak, if your accent is too strong then you are "too African" or if you don't speak your mother tongue then you are not African enough. I had a friend who was so embarrassed because she could not speak Shona (Zimbabwean language) and was so afraid to even try because people would make fun of her.
Yes we have accents, we are from different countries, we are different individuals with different experiences and we are not all supposed to sound the same and being judged by the way we speak is just like judging someone by the way they look.