Ah Iains, like you I've travelled to many African countries (mainly in the West of the continent though) and while I agree that European colonisation has helped itself to their resources, it has also set up many beneficial infrastructures: railways, roads, the Port at Abidjan (designed, built and financed by the French), clinics, schools etc. There have been benefits as well.

And from my and my husband's viewpoint, the corruption BY AFRICANS has been appalling. Once countries were granted their independence, the indigenous politicians promptly set out to milk the place dry. Many of them don't even live in their own 'shit-holes' but have decamped to Europe, while keeping their fingers in the pie back home. They ignore and don't even care about the dreadful poverty they perpetrate. As long as they and their families are rich and prosperous, they're laughing.

There are faults on many sides, and yes, these places ARE shitholes. But is it wise or diplomatic for a Head of State to actually make such an insulting remark in public? Does it not shut off any possibilities for discussion, negotiation or mutual understanding? It's childish, rude and dangerous.
Please don't imagine for one moment that I can't sympathise with the poor refugees and boat people who, as you say, are desperate enough to risk their lives in flimsy boats to get to the Promised Land. It says it all about the conditions at home. I have a whole family in Ivory Coast under my and my sister's protection and help. But the answer is not to insult them. They need their evil blood-sucking ministers ousting and some kind of moral government set in place. They need Aid, and support.
Trump is a fool, a bigot, a racist, a misogynist and a dangerous loose cannon.
(Sorry this is a bit long, but Africa is close to my heart)