Hi Gabriella,
I hosted like Till and Jutta do, my whole apartment in my absence. I offered a shared room a few months ago, intended for a short while as I had to stay in town. In Paris, Europe, I was completely surprised to have so many guests and the experience is different from what I expected.
I met different guests and they are not all budget travelers even if the bed I offer is cheaper as a private room or a private room with private bath or a whole apartment.
Who likes shared rooms? Usually people who hate hotels, people who have to go to a country where they don't speak the language or don't speak it well, people who feel reassured that there will be a person there when they come home at night, that they can chat with over breakfast, get advice what to see, where to go, what parts of the town are dangerous or where can a single female walk at midnight without fear, what do the locals eat etc.
Shared room is more like staying with family: you have to clean up after yourself without delay, you'll have to make your bed daily, because the bed might be someone's living room couch during the day or your hosts normal visitors would see it rumpled otherwise. You'll have to listen to rules a bit more carefully then in an entire apartment, like who can use the bathroom when or how long - but that's usually a question of organising. Imagine living with a cousin and his family when you are on holiday and they work. You could not block the bathroom for two hours at the time when everyone gets up and needs to go to work.
There might be advantages too, like your host inviting you to share (a not included) breakfast or a cup of coffee now and then.
And surprisingly, there is another category of guests I never expected: business travelers. In my cheap and tiny room I host a lot of business travelers who arrive very late - easier to accept for a night owl like me living there, they want to chat on a fast Internet connexion with their family, sleep in a good bed, take a shower in a clean bathroom in the morning, take a cup of coffee or a glass of orange juice and are out of the house before I even wake up. Privacy enough for some.
But as said by others, check your future host's reviews. People are very diffeent and living in close quarters, personality is more important and you need to look for a host which would be a good fit with you.
