When sales associate Suzette Bailey of Real Estate Central in Cross Lanes, W. Va., tours a home with buyers, she knows that if it reeks of cat urine and has groupings of everyday household products like stripped-out batteries, lighter fluid, salt, and empty two-liter plastic soda bottles, the home’s problems are likely to stretch well beyond aesthetics. Such signs are potential red flags of a highly toxic substance lingering in the home—methamphetamine.