One of the best summaries I've heard of her came from Francesco Scavullo, the fashion photographer. After having given several (very funny) anecdotes on how X or Y model needed major makeovers before meeting his exacting specifications, Merv Griffin turned to him and said, "And what advice would you give our musical guest?"
Patti had just performed Ask the Angels in a loose black T-shirt and tight black jeans, no bra (and rather large boobs for her size), and had slipped into a black denim jacket to ward against the air conditioning. Her hair was lightly permed into a dark halo, she wore no makeup. I seem to remember a few tarantella bracelets and/or a small watch.
He looked at her long and hard. Everyone was thinking a) wear a bra, b) get her teeth straightened, d) do something with that pretty face, and e) try to look like a girl for Chrissake!
Finally, he said, "Nothing. Absolutely nothing. She is....perfect."
In the year 1978, with Brooke Shields, Lauren Hutton, Farrah Fawcett-Majors, and Bianca Jagger playing against her, a nation stood in awe.
Oh, and by the way, she's a 'bad seed' Kallikak. Figures.