penders - 7:07 pm on Sep 21, 2013 (gmt 0)
As hinted at, mysql_real_escape() should not return "" (an empty string) unless something else is wrong in your code. Nothing has changed in this respect.
However, whether you should be using mysql_real_escape() (part of the out-dated MySQL extension) is another matter. As mentioned above, PDO is the recommended extension these days. You can then use prepared queries which avoids the need to manually "mysql escape" anything.