@Anonymous
I agree. If the guest was just confused and didn't realise that they had to specify/pay for two guests rather than one, that is one thing. If they thought they were going to get the whole place to themselves, that's another. They will resent you being there, even if they realise it was their own mistake.
One of the worst experiences I had was with two girls who booked one of my rooms and then seemed astonished that I lived here, even though it's very clearly stated on the listing. The thing is, if they miss something so crucial, what is the likelihood that they have read/understood anything else, especially the house rules?
Luckily, back in those days, CS would remove an untruthful, retaliatory review, so at least I had that protection, because it was clear that the guests were the ones at fault, but now hosts are also likely to be stuck with a bad review due to the guest's mistake.