Note that adding comments to otherwise identical queries will typically cause the MySQL query cache to not realize they are the same. See: http://www.mysqlperformanceblog.com/2008/03/20/mysql-query-c... Otherwise, neat idea, I like it.
I think if you just prepend C-style comments (e.g. /* test */ SELECT...) it should still work with the query cache [1]. But leading line comments (like --) will not work [2].