A few signs point to a wet crawl space. There’s a musty smell that comes and goes, floors near the kitchen or bathroom that feel colder or softer than they should, and humidity indoors that won’t come down even with the windows shut. Go down there with a flashlight and you’ll usually find mold on the subfloor, the joists, or the old insulation stapled between them.
Anaheim’s older neighborhoods make this more common than you’d see in newer cities nearby. Craftsman bungalows in the Colony district still sit on their original raised foundations, with old galvanized plumbing that’s well past the age it was built to last. Out in the west-side tracts that went up during the Disneyland-era boom of the 1950s and 60s, that same vintage of pipe is further along and starts failing section by section, and a slow leak under the floor usually goes unnoticed until the smell reaches the kitchen. Winter rain adds to it in both areas: roofs patched over decades let water in around old flashing, and once it’s under a house with no ventilation down there, it doesn’t dry out on its own.