Regards earlier message about Smokey Mountain, officially it's closed, and everyone has been moved on, but they have moved about 200 yards away and another landfill site (effectively the new smokey mountain) exists. We helped out a few times with the charity there run by a British lady called Jane Walker called the Philippine Commnuity Fund. You can buy merchandise made by the people who live there, made using rubbish essentially and is sold in debenhams. I've never had any concerns walking around Tondo, but never have anything worth being mugged for one me!
I agree with Terpe about Lagos, I absolutely hate the whole of West Africa, and have ended up in so much trouble there that I never ever want to return to any country along that coast. Most of Africa is corrupt, but Nigeria, Ivory Coast, Angola and the Congo are the worst.
There are parts of the UK I don't enjoy, but you'll always within half on hour of somewhere nice almost everywhere.