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Had an argument with my wife regarding the propriety of using the expression "wow". It all started when I blurted out the word in astonishment when the preacher mentioned a negative observation. He mentioned that a well known religious leader wrote in a column a negative statement, "how could our country (not the U.S.) claim to be Christian and yet be so corrupt..". I could not help but blurt out "Wow". My wife reacted and whispered to me that wow can only be used as a reaction to something positive. Is she correct?