There was a study I seen on discovery health I think (not 100% sure) but they had a separate group rate a small group of 10 women and 10 men on a scale from 1 to 10. They were able to see anything that you would be able to see in real life. Walking, talking, and facial expressions.
After they were rated the men and women paired off on who they thought they could form a relationship with based on looks. The outcome was pretty surprising. The 8s, 9s, and 10s all were attracted (and went for) higher numbers. While the 5s, 6s, and 7s became pairs just like the higher group. 1s would group with 1s and 2s, 3s and 4s went for each other as well. While no one in this study was particularly ugly, and none were even near obesity everyone had their distinct traits, glasses, freckles, hair color, style, length, and fitness.
They ran this study on a few sets of 20 (10 men and 10 women) to get a more accurate view of things. There was only 2 couples that went for much higher/lower people. While I can see it happens day to day it all really is just personal taste and opinion. One person may like someone with freckles, finding them incredibly attractive, while others are more intrigued by body shape, hair color, face structure, etc.
It was a very interesting study on attractiveness and how / why humans pair off as they do.
Thanks for a great question!