-dit(bf(--delete)) This tells rsync to delete any files on the receiving
-side that aren't on the sending side. Files that are excluded from
-transfer are excluded from being deleted unless you use --delete-excluded.
+dit(bf(--delete)) This tells rsync to delete extraneous files from the
+receiving side (ones that aren't on the sending side), but only for the
+directories that are being synchronized. You must have asked rsync to
+send the whole directory (e.g. "dir" or "dir/") without using a wildcard
+for the directory's contents (e.g. "dir/*") since the wildcard is expanded
+by the shell and rsync thus gets a request to transfer those files, not
+the files' parent directory. Files that are excluded from transfer are
+excluded from being deleted unless you use --delete-excluded.