agree with 20:25 - there are a lot of properties (in the midwest especially) that should be condemned because the presence of a meth lab meant that the house is now a HAZMAT situation.
That would be my biggest worry, but the possible return customers would be a concern too. Our previous townhouse was down the block from a known "former" coke dealer and I'm almost positive he was still dealing, given some of behavior of the people visiting his house. (random cars idling outside his house at all hours, etc.)