Who cares about Detroit - we really want to hear more about his wife.
One thing to look at when buying real-estate is if the area is growing or shrinking in population. That's easily done with census data nowadays on city-data.com or moving company data published periodically in news outlets. Sounds like you had the right intuition even back in the day when this wasn't as simple to come by.
Detroit is probably the worst example, but I do worry too about buying in a place (even to live in myself), if more Uhaul trucks leave full than arrive the other direction.
To JYL's point, let's hope he did a few other investments that were doing better. Real estate is a tough one, as some people have to toss everything they have at an investment property and then have nothing left for other assets. I would not recommend doing that, even if it means you don't hold investment property.
G