
<== Me is dunce.
I forgot to remove the quotes, quotes imply literals which is why the space is part of the filename. But since the wildcard is quoted, IT is a literal asterisk!!!
Properly, these things should be escaped (with a backslash "\") instead of quoted, and the wildcard will work.
Code:
/Applications/calibre.app/Contents/console.app/Contents/MacOS/calibredb add --with-library=/Volumes/Ministack/Calibre\ Library --recurse /Users/IS/Dropbox/Reading\ Books/
rm -r /Users/IS/Dropbox/Reading\ Books/*