Shadowhand said:
I believe the name came from naming it after the cosmetics company because it's supposed to be like (and I have seen sometimes referred to as) a "nailpolish" finish, not a particular color, and as Cagey mentioned due to her popularity. Mary Kaye reps do drive hideous pink cars that are awarded to them for reaching sales goals though, or at least they used to.
Different spelling (Mary Kaye, the artist vs. Mary Kay, the cosmetics pyramid scam). Plus, Mary Kay didn't exist until 1963, while Fender first produced the finish by that name in 1954. So, no connection.
You're right about the pink cars, however. One of my aunts had one. She started off with the Tupperware pyramid and did so well they gave her a car, but it was sorta eating her life and the huge volume of overpriced plastic gimcrackery was eating all her house and garage space. So, she switched to Mary Kay cosmetics and was just as successful, but the product was much easier to deal with logistically. Eventually, she figured out that she was working 80 hours a week and nearly everyone she'd ever met was trying to avoid her, so she got out of the pyramid schemes altogether.