I grew up in Michigan, and I can say with a good amount of certainty: any house in Detroit that is unoccupied does not have a single thing of value left in it, especially copper. Even some places that are occupied have had their copper stripped from them, sometimes live wires that results in the death of the thief.
EDIT: Some links. Copper theft is a big deal in Detroit.
City of Detroit borrowing a page from scrappers and thieves by selling old copper wire to boost Detroit's finances.
Which you can also resell. You could even scrap the ovens for money and water heaters. There is far more motivation to wreck it than upkeep it. All those houses are goin doooown.
Brick can be recycled but I see what you are saying. And hearing that people are getting killed pulling live wires... That would definitely imply that copper is epic loot in Detroit right now.
EDIT: Some links. Copper theft is a big deal in Detroit.
City of Detroit borrowing a page from scrappers and thieves by selling old copper wire to boost Detroit's finances.
http://www.detroitnews.com/story/news/local/wayne-county/201...
Thieves stole copper from functioning pumping stations, leading to massive flooding in Detroit recently
http://detroit.cbslocal.com/2014/08/13/copper-theft-a-possib...
Copper thieves caught in a sting on camera
http://www.wxyz.com/news/local-news/investigations/copper-th...