From the Mind of Trevor Stone

Time can certainly be a fourth dimension in the model. One could periodically make a 3D attraction plot and then show a Time Lapse of Sexiness. "Wow... back then I was totally into type X but I've learned how awesome type Y can be."

Ratings of a particular person also vary over time. After a few dates, someone might say "I met this type 18... I'd say at least a 0.8!" Three months later the comment might me "That type 18 hasn't called in weeks. Downgraded to a 0.3!"

And a person can certainly change position, particularly along the gender spectrum. Changes to sex characteristics are tougher but certainly not impossible.