As scientists have proved, and an awkward encounter with Gwyneth Paltrow has reaffirmed: love it or hate it, the F-word is mighty — Sometime in the mid-’90s, I was sitting in a spa chair for my weekly mani pedi when a milky-pale woman settled into the chair beside me. Her existence hardly registered until she held up three bottles of nail polish, all variations of nude pink. “Which for my fingers and which…