The "spec" isn't exclusive to radio, but we deal with this every day.  This social experiment produced by a Canadian ad firm beautifully demonstrates how any sane, normal, working professional would (and should) respond to the idea that they should provide any sort of good or service sample for free.

For those not familiar with "spec," a spec is a custom-produced sample of work produced for free in hopes that the person requesting the spec will actually pay for material.  There is never a promise associated with a spec.

Here's an example: I would like the home builder to build me a home for free.  That way I can decide if I like the home.  If I like the home, I may buy the home, but, if I don't, the home builder has only wasted his time, money, resources, etc... That seems okay, right?

Here's another: I would like the dealer to let me take a new car on vacation.  That way I can decide if it's a good fit for my family on vacation.  If I like how it suits my family on vacation, I may buy it.  Actually, I probably won't.  Why would I?  My vacation is over.

Don't even get me started on "added value."