nepotism anybody?

What do you say to someone who offers to give your name a boost when it comes to school admissions and jobs?

I've said no to all three times this has happened to me and I wonder if it's stupid of me. But, as with anything I do, I would like to know that it was my achievement and not someone's fundraising or job title. And I think it would actually do little good for me... but it still makes me wonder if any of it would have helped.