It's a real phenomenon, it changes the eyes/gaze from a somewhat (semi-)innocent and happy/good-willing expression (0 - 10 notch count) to a soulless but sometimes actually enticing (in the sense of pure superficial lust) deep and restless stare (100+ notch count), just waiting to ravish their next victim. It may need its own field of research but it's definitely real. They are often still somewhat reasonably attractive (hence the high notch count), that's why Rachel doesn't have one (and she's lesbian anyways) but the potential for a long term stable soul mate is long gone.
1000 Cock Stare to female's relationship ability is like Type 2 Diabetes to obesity these days. You used to see them on C/B List Movie stars or Executive Women/Former Sorority Girls/Car Models entering their 30s, now you see it on women in their mid 20s.
Although this is Stage I or II of 1000CS, not full blown 1000CS