I assume spoof covers are those thin plastic things you slip over your CDs to prevent spoofs from settling on them?
Anyway, I should point out, as a veteran of the Song Challenge circuit here at Mudcat, that almost all the Song Challenge entries over the years have been spoofs in which an old song is borrowed and wrapped around a current theme of some sort.
Just meandering among the Song Challenge Winner entries in the Mudcat Song Book (see links above) will give you more spoofs than you can shake a stick, or any similarly shaped appendage, at.