This is actually I think how Airbnb was originally supposed to work... You rent out a room or an in law suite that you aren't otherwise using. Or maybe your condo in a resort town when you're not there. Unfortunately became so lucrative that you can make more money doing that than renting. I stayed in one in a ski town recently that was clearly at least two separate apartments before and had all been combined to house large groups. Felt kinda crappy about that, and it goes to show how it eats up the housing stock