I know several folk, Celtic, blues and bluegrass radio DJs and they all say they're constantly being inundated with more CDs than they can possibly use. So, if that Celtic DJ is just playing the same stuff over and over again, it's probably because she's lazy and/or uncreative.

That being said, the DJs that I know are all open to receiving good music and will play unknowns alongside the "stars" if the music holds up. Of course, they're all on community, college and public stations.