"A straw vote only shows which way the hot air blows"

This quote by O. Henry is a metaphor for the concept that a straw vote, or a preliminary vote taken to assess popular opinion, is not a reputable indication of the true viewpoint of the public. The phrase "hot air" is utilized to represent the viewpoints of the general public that are not based upon truths or evidence, however rather on feeling or hearsay. O. Henry is suggesting that a straw vote is not a trusted step of public opinion due to the fact that it is based on the viewpoints of a small group of individuals, and those opinions may not be representative of the bigger population. He is suggesting that the results of a straw vote can be quickly swayed by the viewpoints of a few individuals, and that the results of such a vote may not precisely reflect the viewpoint of the bulk. O. Henry's quote is a reminder that a straw vote is not a trustworthy measure of public opinion, which it should not be utilized to make important choices.