I think they call that "Buying the wrong demo"

[Don A]

>>
All during the time period during which "progressive Talk" was programmed
on WXKS-AM 1430 in Boston/Everett and WKOX-AM 1200 in Framingham, many of
the local insertions for Jones and Air America shows included Geico spots..
>>

They could have:

a.)  been inserted by the local station as part of a (anohter) network 
affilliation. (Say, WW1...or from Clear Channel National Sales) and therfore 
part of a national buy.

b.)  inserted by the network into the local stop set.  CNN used to sell (at 
a big discount) the stopset that was set aside for local insertions....with 
the idea that some cable systems would run the stop set as is, when they 
didn't have anything local to cover it with.