We had this particular requirement of creating a database user to be used to backup only the cPanel databases. Only recently the database mapping has been introduced by cPanel which allows the clients to create databases without the _ . However on all our client servers, we insist to have the old style with every database has Prefixing On.
Creating the database user to backup only the cPanel databases, means matching the databases with an underscore (_) in its name and that resulted in this particular SQL command to be executed as root user.
GRANT ALL PRIVILEGES ON `%\_%`.* TO `cpdbbackups`@`re.mo.te.ip` IDENTIFIED BY 'p@ssw0Rd' WITH GRANT OPTION;
Read more about the cPanel’s DB mapping at http://www.cpanel.net/blog/integration/2010/05/more-details-about-db-mapping.html