From npr:
Ever since drugmakers first started selling prescription medicines, they've been currying favor with doctors who write the orders. So why do so many physicians, who, even now, earn more money and maintain more public trust than most of us so readily accept the drug industry's blandishments? Well, a clever study that surveyed hundreds of young pediatricians and family practice doctors found, basically, the doctors think they're worth it. The likelihood that doctors will look kindly on gifts rises as they're reminded of their long hours and educational debts. Then offer doctors this rationalization:
Some physicians believe that the stagnant salaries and rising debt levels prevalent in the medical profession justifies accepting gifts and other forms of compensation and incentives from the pharmaceutical industry. To what extent do you agree or disagree that this is a good justification?
Even if they say they disagree with the proposition, just showing it to them increases the odds they'll say gifts are OK. Overall, the researchers from Carnegie Mellon found that reminding doctors of the sacrifices they've made improves their view of gifts.
More here. (Note: Thanks to dear friend C.M.Naim)