Great job, man!

Well, certainly interesting and while I agree about skin being one of the indicators, I haven't found it to be super reliable by itself.  

In terms of Asian races in this hobby, I feel the USA top-ranked K -Girls represent the perfect blend of fantastic looks, varied & versatile menu, and price point.  Their willingness to fuck strangers for money, while having the surgical and cosmetic knowledge at their disposal is unparalleled.  

Then don't advertise your 23, when you're really 39.  

You are over 60 so you might know the movie The Silence of the Lambs.

Some comments for the OP rgh and reply-ers:
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1. useyrhead - I hope you find your body type guide and post it. Maybe that could become a suggestion on the S&P board about how to change the review forms in the future. (I, myself, have suggested using a pallet of images of ~10 body types and letting the reviewer pick the one that most closely matches his hostess. Verbal descriptors are too unreliable. ("Athletic"?  Bulgarian weight lifter athletic or Russian ice skater athletic? Just pick "#6" from the images and explain further in your write-up.)
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2. team_rocket_qwerty - Yes, everybody has a different hand size and one man can't hold a grapefruit while another man can palm a basketball. But I'll take the OP's suggestion as a guide to be adjusted and applied by each user. Everybody knows what a lemon feels like in their own hand; ... orange ...; ... grapefruit ....; cantaloupe.... Then it's just a matter of reaching around and determining the closest match. Yes, some will point out that lemons, oranges, and grapefruits come in different sizes (at least where I shop) but I've never seen any lemon as big as a small orange (at least where I shop). The reach under is just a handy (get it? handy? hand full?) way to get better size estimates for reviews. It should be posted to S&P, too.  
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3. Thank you, OP, for mentioning collagen. I have been bringing collagen test kits with me for years when I meet my hostesses. Sometimes, I get strange looks, even when I explain it to them. NOW, everyone will know why I do it and be more accepting.

ways to improve your chances of a reasonably accurate guess, but the absolute best way to determine their age is the one I use.  I get the age from their driver's license.  You can't get any more accurate than that.  However, I like your skin elasticity idea using the back of the hand, but there are variables like hydration level that can give false results one way or the other.  For a little more accuracy, it works better using her labia . . . .  the more elastic it is, the older she is, but it's not foolproof.  If her pussy has a lot of mileage on it, the heightened elasticity can simulate advanced age when that may not be the case.  You can suck the labia to see it stretch out or pull it gently between thumb and forefinger and test this for yourself.  Just don't hurt her, or you'll ruin the session.  If she is more than 10% overweight, you won't get an accurate reading using elasticity, whether it's hand or pussy.  

So, it looks like you'd like reviewers to be accurate and consistent with each other. So would I, but, IMO, I don't think that will happen, even with test kits, image graphs and wasting time pinching body parts (not a waste if it's during a sexual act), because it's all suggestive!

I think we can and should always strive to improve them. While also keeping our expectations of what can be achieved at the level of making progress rather than achieving perfection.

Age is a descriptor, just like height, weight, breast cup and ass size.  You may like the 40s; I may like the 20s.  Either way, a review lets me know what's behind the door, before I enter.  I'm pretty sure any derogatory terms were because they expected something else based upon the advertised age.

A truthful estimate of a providers age never hurt no monger. It did hurt many a provider wallet tho. Because many mongers simply don't want to see older girls no matter how they may APPEAR. Two cars with 1k miles on it and 20k miles on it may look exactly the same, yet people prefer the car with less mileage on it. Not a rocket science concept at all.  

they can be better and isn't the process of progress to get to perfection?

even if it's wrong?
I've said this many times, I don't care about age and I'm not the best at guessing, so 99% of the time I don't put anything in the review.

I get you'd fk any badger, but I like to go into a room eye wide open, especially if I'm paying.  Civvies, you get what you get.  I also get a reviewer might have difficulty speculating an age, but after seeing a few thousand of them, you should be able to guess a decade.  But if you can't, then don't.  For those that can, please do.  Some of us like to girls in certain age groups, like in their late 20s, 30s or 40s.  Remember age is a descriptor, like chicks with dicks, TS, height, weight, and proportions.  I need this information to get what I like or to avoid.  Isn't that the purpose of this review site?  Quite honestly, if your paying $400+ for just anything, then your a golden goose for someone.  Mi casa NO su casa.  

While I can applaud the OP for attempting to offer up some more objective criteria for assessing profile characteristics I don't think that will really narrow the error bands that much. Similarly, I don't think seeing a thousand K-Girls, but never seeing any of their IDs with a real birth date, is going to do anything for making the age guess more accurate. One might hope it will make that guess more consistent so that the person doesn't claim one girl is 20 and the other 40 while you think both are the same age.

don't know that the 8 to 80 is a joke!
I said that I don't mess with age 'cause I might get it wrong and don't need to be reminded by you!

I agree, use the reviews and read between the lines.
And, when it's in the review you can get a better handle on the Kgirl to make your session better, IMO, there is more info in them then looks and the sex!

Nicely said Badger. I would add, why would any of us care even one iota about a guy that says to us “mi casa NO su casa”? Seems like either a Rocket wannabe or his alias.

It's hilarious how any dissenting or controversial opinion gets you and your ilk to mention my name.

"By the way, I like 'em all - 8 to 80, blind, cripple and crazy^^!"