when an israel day care center decided to tack on a fee for parents who were late in picking up their children, the number of these late parents increased rather than decreased. it turns out that once you made it a financial transaction, the social/moral stigma of being late for your child was removed.
in another study, where a six pack of coke and a plate of dollar bills was left out in the open unattended on each floor of a college dormitory by the end of the day the six packs were consistently taken but the dollar bills were left untouched. it turns out the more disassociated the crime was from monetary theft, the more likely it would occur.