I tried looking this up in past suggestions and didn't find it, so I'm making a suggestion:

The "Looks" is purely in the "eye of the beholder"....   My "10" score might be a "7" to you, right?

Performance Scores:  The gal might just not like the way you look, smell, act, etc.  However, averaging out the many reviews of a gal, one can obviously see a pattern and figure out that it is not the gal, rather the monger is just a dud.

How about a "Value" score?  A gal might be "so-so" in looks, be an absolute killer in performance due to chemistry, overall attitude, etc......   but, her "Value" might rate an "8", due to her demand for $1,000-1,500-2,000 per hour?

The current categories are already fuzzy enough. And "Value" is an even fuzzier concept. So I vote for another measurement: The GaGambler Score. GaG was a notoriously hard grader and he would typically grant a girl who got 9s only a 7 at best.
Note: This is not a serious suggestion, in case you didn't know. LOL

iagree with inicky. "Value" is just another subjective score. Compare that to objective info that can influence a decision: height (do I like tall or short?), hair color (do I like blonds or brunettes?) and so on.
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Some might give your suggestion a value score of 0. Some might give it a value score of 10.