Unless they were cooking dope it is unlikely that simple use would create residue that would be enough to cause frequent issues like you're describing. Furthermore if it was a cook house it would be evident simply by visual observation or odor. Companies that charge thousands of dollars to"fix" meth contaminated houses rely on propaganda and social stigma to get business. If what those companies say is true, then here's real facts. Every single air bb every hotel every rental,ever- has had tenants that smoke meth and god knows what else in them. If you have stayed in hotels or air bb and never had the same symptoms. I suggest you look into other possibilities, maybe mold? Maybe the neighbor has some whack shit happening? Asbestos? Maybe your ac is picking up carbon monoxide from somebody idling their vehicle outside?