Upon researching travel in Africa, I came across some important warnings that I think everybody should know before they travel to Africa. None of these are from first hand experience, just from what I have found online.
1. Police asking for bribes.
2. In Kenya, it is illegal to take pictures of the President and his possessions.
3. Taking pictures, in general, can be risky.
4. Be aware of your surroundings, even if you are in a car. It is easy to get robbed.
I cannot say for sure, like I said, I was doing some research and came across this information. While some of these are general things to be cautious about, I found them in regards to Africa, and decided to post them just to inform others. While you may be aware of these things and are careful, others may not be as lucky.
I was advised that it is wise to always have on you the phone number of a good local lawyer if you are travelling in South Africa. I think that this is wise advise.
it's not only in Africa
the things you said can happen anywhere... Africa is a continent, president from which country are you talking about? I frequently travel in Morocco and I never had such experiences... that means I'm real careful , right? :)