Test, do not assume. Especially on a flip.
A repainted Arcadia flip is a hypothesis, not a finding. I order four things before we release the inspection contingency: a sewer scope, a moisture survey of the envelope, an HVAC load verification, and a panel identification. Cosmetic work is easy to see. The expensive failures are always behind drywall, and thirty years of laboratory work taught me that the untested assumption is the one that costs you.
Water chemistry is a line item, not a detail.
Phoenix municipal water runs hard, roughly twelve to eighteen grains per gallon depending on your zone. That mineral load shortens water heater life, scales fixtures and coils, and quietly raises your maintenance budget for as long as you own the house. I check for treatment at every showing and price its absence into the offer, because adding it later is real money.
Microbial risk lives in the building envelope.
Monsoon intrusion, an HVAC condensate pan that never fully drains, an irrigation line run against a stem wall. These create exactly the warm, damp, undisturbed conditions I spent three decades culturing on purpose. On older homes with crawlspaces I moisture-map before we write. It is inexpensive, it is fast, and it is the difference between buying a house and buying a remediation project.
The build year tells you what will fail.
This is materials science and it is knowable. Polybutylene supply lines went in between roughly 1978 and 1995. Federal Pacific and Zinsco panels carry documented failure modes. Galvanized supply in pre-war Phoenix homes is at the end of its service life. EIFS stucco needs a drainage detail that was frequently omitted. I read the year built and know what to look for before I walk through the door.
Change one variable at a time.
When a listing is not moving, most agents change price, photography, and staging in the same week, then have no idea which one mattered. That is a ruined experiment. We change one input, hold the rest constant, measure showing-to-offer conversion over a defined interval, and then decide. Slower by a few days, and dramatically better at finding the actual problem.