Why Was She So Suspicious?

Riddle: A woman is sitting in her hotel room when there is a knock on her door. She opened the door to find a man whom she had never seen before. He apologized saying that he got the wrong room that he thought that it was his room. He also said that he was staying alone. He left and went down the elevator to leave. The woman went back into her room and called security. What made the woman so suspicious of the man?

Answer: You don't knock on your own hotel room door, unless you are staying with someone else, but the man did even when he was alone. Source: https://riddles.com/index.php/4832

A woman is sitting in her hotel room when there is a knock on her door. She opened the door to find a man whom she had never seen before. He apologized saying that he got the wrong room that he thought that it was his room. He also said that he was staying alone. He left and went down the elevator to leave. The woman went back into her room and called security. What made the woman so suspicious of the man? — Why was she so suspicious? by Isabel Gisclair Riddle