What is the second clue that something is not right about the paw?

The second clue that the monkey's paw is dangerous is the fact that the second owner tried to burn it. He attempted to burn the paw even though he still had three wishes....... something is a little fishy there!

The second clue that tells us that something is not right about the paw is that when the the two men finished their pipes the atmosphere had changed within a few hours from happy and joyful to depressing silent this show the clue and foreshadow of the nasty consequences which can occur by wishing on the paw.