I too have travelled in Africa extensively. If you are there for some time, you get used to it and after a while. don't even notice it. But it can come as a very unpleasant shock, when it is encountered in a part of the world where it is unusual. That is compounded many times, when faced with the prospect of being forced into close proximity to it for 10 or more hours
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This isn't really a PC thing, but more a question of regional social norms. But how do you deal with it? Personally, I think people should be screened at check in or at the gate, in the same way that people are for being drunk. If it is noticeable enough that the staff are aware at that stage, then it WILL become a problem on board, when you are up close and personal.