My MIL had a swamp cooler in Fresno back in the late ‘70s. Worked great but Fresno’s humidity was usually in the teens. Any humidity above about 50% the swamp cooler just put mold on the walls. Lol.
Oh yeah, and they are also known to be a potential source of Legioneer’s(SP) disease.
I lived in Fresno in the mid 70’s and remember one summer it was 109 at midnight. Good thing we had AC back then.