You have to do a little research and know your market. R&B singers, jazz singers, country acts, pop divas, boy bands...pretty much all buy their material. Rock and blues acts hardly ever use other peoples songs.
I don't think it depends too much on having an allready established reputation like "theonewhonoticesmistakes" is talking about, a good song is a good song, and someone who likes your song is not going to choose not to record it becuase they never heard of you...that's crazy. If your material is solid, and you present it nicely packaged and pro-recorded you should be cool.