Drug inspections are out of the scope of the standards of practice ....BUT WHAT WOULD YOU DO ?

Being in a meth lab is unhealthy under any circumstances, including when it is during a home or environmental inspection.
As a heads up, If the three prior sign-ins on the Realtor sheet are DEA........you might be in a meth lab (Drug Enforcement Agency)

Being in a meth lab is potentially toxic for inspectors, buyers, Realtors and anyone else that enters the home.... the chemicals can poison you if they don't explode the building first

What's In Meth
Acetone. Nail polish remover or paint thinner. Extremely flammable. ...
Lithium. Used in batteries. Lithium seriously burns the skin upon contact. ...
Toluene. Used in brake fluid. ...
Hydrochloric. Acid. ...
Pseudoephedrine. Decongestant found in cold medicine. ...
Red. Phosphorus. ...
Sodium. Hydroxide. ...
Sulfuric. Acid.

Back to the meth house inspection. It was a foreclosure so it was a "I know nut-ting" Sgt Schultz disclosure
Oh, about the foreclosure...the prior owner had full room and board courtesy the Feds..didn't need to pay their mortgage ........

But how do you even have any proof to convince your client that they should pay you for the test to prove absence/presence of trace meth?

I have attached two pictures of the bathtub drain ......rotted out by the meth.....(or some other toxic and corrosive test
It had a cast iron bathtub. The porcelain finish was worn off the bottom of the tub. The house was less than 10 years old ...so no...it was not worn off by bathing the kids.

There is very little that can be done to clean up a place so that is safe. This particular place had a septic system which would also hold and vent drug residue

Now...look a the list of ingredients above again ...consider the level of education of most persons engaged in "independent laboratories" and the probably intoxicated state of these lab technicians...........yeh

Back to "outside standards of practice" .....house was cheap ....family wanted house......to raise their children

WHAT DO YOU THINK I SHOULD HAVE DONE?

I would have to consider my approach and wording. However, I would make sure that they were aware of the potential issue. I couldn't live with myself if I knowingly allowed a family to move into a home that could negatively impact their health.