Many hotels ask you to provide your last name and room number to use the WiFi.
In the US, three percent of people are named Smith, Williams, Brown, Johnson, or Jones.
Therefore, in a hotel with 50 rooms, there is a 78% change that one could sign in by just trying these names on each room.
In fact, when I tested this last, using only “Smith”, it took only ten rooms.
Your results may vary.