Music library effect on copyright value?

[doughnutsrule]

I just read the book "The Plain and Simple Guide to Music Publishing" by Randall Wixen, and the author has me wondering whether music libraries can be detrimental to the value of a song that might be chart-worthy. I envision a recording artist or record label not wanting to touch the song because of its prior utilitarian uses.Wixen explains that music is often undervalued, not only by licensees but by the creators/licensors, and that copyrights should be handled very carefully so as to not restrict possible, much larger, future earnings.Any thoughts on this?Jeff