If a us citizen married an illegal alien who was offered money & he accepted as he was on drugs but did not co-habit with bride

Upon learning facts described in your question, the government would be inclined to conclude that the marriage was entered into for fraudlulent purposes. The punishment can be Imprisonment for up to 5 years and a $250,000 fine. To be convicted for marriage fraud the government would have to prove 1. the person knowingly entered into a marriage; 2. marriage was entered into for the purpose of evading immigration laws; and 3. the person knew or had reason to know of the immigration laws. The bride could be removed from the United States in the scenario you describe