I’ve had a love affair with this foundation for practically 10 years now. Chances are, if we bumped into each other at — UGH! — The X in San Francisco in the late ’90s or early aughts (it was a place Jen and I used to go clubbing, and in retrospect it was pretty gross), I was wearing MAC studio fix fluid foundation ($29) on my face and partying all night long. Studio fix fluid is one of those foundations that you can put on your face, and you know that no matter what you’re doing — dancing, sweating, making...