Winter rain and the flood-car problem
The tells are specific. Silt lines inside the spare-wheel well and under the boot carpet. Corrosion on seat rails, seatbelt anchor bolts and the metal frames under the seats, places that never rust on a dry-climate car. Fogging or watermarks inside headlight and tail-light housings. A musty note under the new-car fragrance, strongest when the AC first starts. Mud traces in wiring-loom connectors under the dashboard and in the fuse box. Electrical gremlins that come and go, because corroded connectors fail intermittently rather than all at once.
The seasonal angle: flood cars enter the market in waves, typically two to six months after a major storm, once repairs and paperwork clear. If you are buying in the autumn after a wet spring, brief your inspector explicitly to run flood checks, and ask for the car's insurance claim history where the seller can provide it. A car registered in a flood-affected area with a gap in its service records around the storm date deserves extra suspicion.