When creating a new table with both the EXTERNAL and LIKE clauses, the new table does not behave as an EXTERNAL table thus resulting in potential data loss.
create external table test1 (VAL string) location '/user/craig/test1';
create external table test2 like test1 location '/user/craig/test2';
drop table test1;
/user/craig/test1 - still exists
drop table test2;
/user/craig/test2 - is deleted (bad)
If I do an extended describe on both tables, test1 shows up as being external while test2 is a managed table.