What this video covers
The clip takes on the assumption that a dry climate rules mold out.
Evaporative coolers work by adding water to indoor air, which is the opposite of what a refrigerated system does. A house in a desert climate running a swamp cooler can hold higher indoor humidity than one somewhere famously wet.
The takeaway
Outdoor climate is not indoor climate. What matters is the humidity inside the building, and plumbing, appliances and cooling choices set that regardless of what is happening outside.
Read the full written guide: How to Recognize a Mold Problem.