You know why those areas stay ruined? Property taxes. Lot of those abandoned places have huge back-taxes bills - and the city of Detroit will not admit that it's not likely to collect on them. Also, it won't issue a building permit unless the back taxes are paid up. In full.

For these reasons, a "$1 house" will cost in the low six figures before the reno.

I don't know what the status is for a former house turned garden. Those gardens may have begun as property-tax dodges; I don't know.

Detroit is a classic study on what makes ostensibly cheap real estate a "value trap":

1. High rate of violent and/or property crime (eg. the arson);
2. A dog-in-the-manger local government.