Historical clue formulations

• Bacteria-free — 2025-10-14
• Beyond clean — 2024-11-08
• Lifelessly dull — 2022-06-14
• Beyond clean — 2021-03-18
• Producing zip — 2014-01-25
• Not being productive — 2008-11-22
• Germ-free — 2007-10-08
• Unfruitful — 2006-03-09
• Barren — 2005-09-17
• Germless — 2004-09-06
• Germ-free — 2003-04-08
• Unproductive — 1998-11-26
• Unyielding — 1998-07-11
• Like a mule — 1997-07-13
• Lacking originality — 1996-11-30
• Free of germs — 1996-05-06
• Hospital-clean — 1994-10-12
• More than clean — 1994-06-26
• More than dull — 1994-06-02
• Germfree — 1994-04-10