With a clean conscience: cleanliness reduces the severity of moral judgments.
“However, recent research has demonstrated that incidental feelings of disgust can influence moral judgments and make them more severe… After having the cognitive concept of cleanliness activated (Experiment 1) or after physically cleansing themselves after experiencing disgust (Experiment 2), participants found certain moral actions to be less wrong than did participants who had not been exposed to a cleanliness manipulation.”
UPDATE: From the M&Ms (thanks to an Anonymous commenter):
“Immediately after the priming task, participants rated six moral dilemmas (as used by Schnall et al., 2008): “Dog” (eating one’s dead dog), “Trolley” (switching the tracks of a trolley to kill one workman instead of five), “Wallet” (keeping money inside a found wallet), “Plane Crash” (killing a terminally ill plane crash survivor to avoid starvation), “Résumé” (putting false information on a résumé), and “Kitten” (using a kitten for sexual arousal). Participants rated how wrong each action was from 0 (perfectly OK) to 9 (extremely wrong). Participants subsequently indicated their feelings at the moment for the items relaxed, angry, happy, sad, afraid, depressed, disgusted, upset, and confused, using a 10.5-cm visual analog scale labeled “Don’t feel at all” at one end and “Feel very strongly” at the other. All scales were scored by measuring in half centimeters from the “Don’t feel at all” end, yielding raw scores ranging from 0 to 21.”