You could go crazy figuring out the oddities in homes.
An inspector I know got called out for "resoiling" problems on a carpet. The carpet was filthy, and due to debris, obviously not vacuumed.
He tactfully asked how often they vacuumed. The complaining consumer confidently replied "daily". Now even more tact was needed (as it obviously wasn't true) so he asked to see their vacuum cleaner, to determine if it was in bad repair.
They said: "We have a built in system"
He asked to see the tools.
"What tools? We just open the ports and turn it on...why?"