@Val4201 If it happens a lot I would also add it in your messages to guests (I do), I have had a few close shaves and even been penalized because a guest retaliated and wrote a nasty, dishonest, 1star review because they couldn't sneak in extra guests.
Some guests never get as far as reading or taking note of host's rules. Reminding them of rules on arrival is often too late and the host is then forced to take the full blast for the guest's failings: guest is annoyed or worse; guest cancels and Airbnb refunds the guest; Airbnb allows the guest to leave a retaliatory, dishonest, low star review and won't delete it, because it is deemed useful to future guests, thus the host is penalized for a guest's wilful error, dishonesty or worse.