Sharks don't like people

For some reason I was thinking about alligators eating people today, and kind of let the mind wander a bit.

Experts always say that sharks (and most other big predators) don't like the taste of people, and only eat us by accident. Seems like a pretty big accident, and I'm sure the victims don't feel relieved by it being an inadvertent mistake. More importantly to my twisted mind: how do scientists know we taste bad to sharks? Is there a taste test they do? Some sort of aquatic predator version of the Pepsi Challenge? I don't get it.

Maybe that wacky Steve Irwin would know...