[Jaydelart]

He must not have been at home often.
She said she snuck in when he left his door unlocked, which, maybe, suggests that he leaves often.
This is, afterall, the door to his house he's forgotten to lock. She even admits to taking showers there.

... Or perhaps I'm wrong and that isn't the case...
Instead, she may just have incredible stealth skills for a 58-year-old woman... or is just incredibly lucky (with the exclusion of the possibly convenient fact that he's often away).

Of course, one could always simply claim the man was stupid... But I'm trying not to immediately accept that as my conclusion.

Eitherway, the fact that she even lived in his house for one year, without getting caught, is amazing.