"Seriously, who does that?!"
A few unfortunately but you are not alone.
My parents have a holiday home on a popular island in France, and they often had people inviting themselves over. When my parents lived in England (they have now reitred to said holiday home) quite a few people would say to them, "It would be good to see you in France". My mum's response was, "why? You get to see me daily here in (name of town)".
However, the one occasion that REALLY rattled my mum was when a family of 4 (whom we barely knew) invited themselves to our holiday home. At the time, I was 8 or 9 years old. The first we knew about the family coming over was when the taxi driver (who knew us well) stopped me in the street (I was riding my bike, having just been to the 'Boulangerie') and said, "is your mum at home to pay the fare? They don't have the change" looking towards the back of the taxi.
I looked over the taxi driver's shoulder to see the family, who all smiled back at me. Anyway, when I got home, there was an almighty arguement between my dad and mum. Mum was insisting that the family should book themselves into a hotel. Dad was trying to calm her down saying, "it's only for a few days". And yes, mum and dad did pay the taxi fare. The family did stay for 3 days (3 days of hell for them) because my mum refused to play host.
I think for the uninvited family, the last straw was on the morning of the 3rd day. The family were setting off to the beach, when the father/husband asked my mum, "when do you want us back for lunch?" My mum replied, "up to you. Back in time for whenever you intend to make your own lunch!"
They left the next day. Word must have got round because never again did my parents get uninvited guests.