They could set up an "abatement" system, I believe there is one in certain sections of Dacula, and I know of it's existence in a number of suburbs here in the MidWest.
The city can tax/fine unmaintained properties into oblivion, then either seize the property or fine the mortgage company so much they oft-sell it to the city.
Helps keep property values up, and rewards property upkeep.
Chicago has a program sorta like that, but they couldn't have the liability of selling damaged/abandoned homes. Commercial properties they'll auction normally. So what they generally do if they end up owning a abandoned single family home in bad shape is they tear it down and will sell the land for $1. Normally they try to sell it to the owner of one of the properties directly adjacent with the expectation it will be upkept and they pay property taxes.
Unfortunately here, a majority just end up bank owned and bought at foreclosure auctions and held by investors who sit on them and don't care how they look can they're in it for the land.