I don't know about you, but I would pay ALOT less money for a house with known HARD drug users as neighbors.
So you're going to go with property values rather than "social costs" or misspent tax money.
Contrary to what many people think, including many libertarians, the most important thing about property is not that you can sell it but that you can use it. It's that confusion that creates violations of property in the name of property, such as zoning ordinances.