I tell people I don't take passengers, I take crew, and that they may be assigned jobs. In return, I usually cook the dinner back at dock.
Now, do I take "crew" on anything more than 12 knot days? No, not usually. Do I really need them to work the boat? Hardly. But to a culture where the young people are all too acclimatized to getting hauled around by car or van, handing a kid a sheet and showing them what "clockwise" means on a winch is practically a public service.
That and disabling the DVD player while we're underway.