If the kitchen is too small for a family sized dinning table then a dining room may be used every day. 

Rent by the room is a great strategy for cash flow (I house hacked my first house and did exactly this). 

If you want to get into this business, you need to get really good at advising your potential clients on how they can best accomplish their goals.All of this is true for whole home rentals or room rentals. 

There seem to be multiple cracks in the walls of all the rooms.

A couple thoughts here... medium (monthly midterm) tenants stay 90 days on average which is only 4 tenants a year leaving plenty of room in the market if you have professional photos, quick response time, reasonable pricing and fees.

I'm looking to acquire my first co-living / rent-by-the-room property.

Hello, I would like to rent out a few rooms in my house, does anyone know of a company I could use that will do the initial background checks and lease write ups?

Don't forget to book your room at Caesars Palace before we're out!

Rented room for several years, never advertised, no sign in lawn, no posting online anywhere.

You can hire someone to rent the room like a PM company for fee but it is hard to find people who will handle rooms and the catch you are exempt from fair housing if you live there and don't use a relator so there is that.