He did a lot of house sitting. He was trustworthy, and people often asked him to watch their homes when they were away.
He was good at it.
He also stole something from every house he stayed at. He stole a
toothbrush, usually. Just a single toothbrush. A single, used
toothbrush.
People thought they had brought the toothbrush with them, and left it
behind at their hotels. And left it behind at the cabin in the woods
where they stayed. And left them behind at the home of one of their
relatives.
But, no. He had them.
If you went into his apartment and opened his medicine cabinet, you would find dozens of toothbrushes.
He never used them. He just kept them as mementos.