Historical clue formulations

• Result of a permanent failure? — 2011-01-21
• When one might wear a hat — 2006-10-09
• Result of improper conditioning? — 2002-03-30
• Coiffure crisis — 2000-05-22
• Reason to wear a hat — 2000-02-12
• Reason to wear a hat? — 1996-02-15