Then, I saw in the Amarok playlist menu a way to export to a file! Just add all the tracks you don’t like to a PLS file using the Export Playlist As… option, and run the following, replacing what’s necessary:
grep -E "^File" todelete.pls | cut -f 2 -d = | while read a; do mv "$a" /nexus/tardis/Music/BADBADBAD/; done
And you’re done!
hank@tardis:/nexus/tardis/Music/BADBADBAD$ du -sh 54G .
I think a 54GB savings is pretty darn good!