One bedroom rentals and tenants

[Robert Howard]

I just wanted to get the consensus on what the community thought about one bedroom rentals? Please share!  I'm thinking about purchasing a duplex side by side 1 and 1 both sides, but the owner is house-hacking.  He advised that his last tenant just up and left.  He also advised that even when he sells, he wants to stay.  Something doesn't really set well with me with that statement. So any advice would be appreciated.  Also what are some of the questions I need to ask the owner to make sure he isn't hiding anything.  I guess this is a two part question.