Stealth deducing George is a janitor

“I generally do not associate with janitors.”
His heart lurched back up in his chest. “You know I was a janitor,” he said.
Karen pointed at his hand. “There are seven round spots on your right sleeve,” she said, “each discolored to a different degree. They are from drops which splashed up when you were soaking a mop, and do not appear on your left arm because it would be held higher from the bucket. The discoloration was caused by a diluted industrial cleaner, meaning you were most likely not mopping at home. The varying degrees of discoloration mean it happened multiple times with different ratios of water to cleaner. Mopping is a regular action you perform when not at home, thus, a janitor.”

Excerpt From Ex-Purgatory, pg 205
Peter Clines
https://books.apple.com/us/book/ex-purgatory/id676938479