Historical clue formulations

• Smooth — 2024-06-20
• Certain ocean pollution — 2023-05-17
• Nifty — 2021-04-21
• Cleverly crafted — 2015-06-28
• Like pomaded hair — 2014-02-04
• Like a recently waxed floor — 2013-12-16
• Rain-covered — 2006-06-14
• Oily — 2001-08-02
• Like a snake-oil salesman — 1997-10-21
• Deft — 1997-05-24