The truth is that everyone judged people by their appearance first.
One good example was Heavenly Dragon. At the start, he was looking proper and everyone wanted to get close to him. After he transformed, everything changed.
That look of his resembled Mario, and nobody would doubt him of eating humans.
Originally, there were not many players outside the mansion. After Apocalypse's announcements, more and more people gathered.
People were already curious at the situation of having so many players block the entrance, but the announcement fired up the situation even further. Everybody started commenting about what was happening within their groups.
There was a saying from China that goes, "Three humans make a tiger".
At the start, no one believed that the City Lord would kill people, but after more people started talking about it, everyone started being curious to know if he really did it.