Hello,My name is Elyse and I am currently pursuing my undergraduate degree in Chemical Engineering  at The University of Arizona.

I work in a chemical plant so the stuff I work with isn't really the best for me either.

Speaking of costs, if I did have a rental with a pool, I would factor in the cost of you (the landlord) providing/paying for the regular maintenance and chemical treatment because tenants aren't likely to do it (at least not properly). 

If he has been living in the house for 20+ years and is a moderate to heavy smoker, there may be rooms where scrubbing, sealing and painting simply won't keep the chemicals from coming to the surface and you will end-up pulling down the drywall and hanging new.We renovated a house some years ago where the former owner had a favourite chair in one corner of the living room where she sat and smoked.  

Last suggestion is to find a couple chemical suppliers in the area and talk with the chemical reps.

You can search this registry to see if DEA did a "cleanup" of the property:http://www.justice.gov/dea/clan-lab/clan-lab.shtmlI've seen 20/20 or 60 Minutes episodes that showed the residual levels of hazardous chemicals present in structures used as meth labs.

My day job is a power engineer for a chemical manufacturing company, but in the evening I read about real estate.

I suppose the oil slump won't hit that area as hard, because many of the people in that area are tied to the downstream side of the business (refining, chemicals, etc.

I know chemicals are expensive for large pools that are well used or with debris getting in, trim branches yourself.my nickle's worth

Standard fasteners typically corrode over time, when exposed to the chemicals infused in PT lumber, which can lead to fastener failure.That being said, the basements of old were framed using standard lumber, and typically have held up just fine!