it is all based upon one's perspective.........and in the example you cite.........seems to be a very consistent perspective for the hobbyists who have visited her.

But by definition it's someone who by their appearance and actions stands out in a singular way, such that you may never again meet someone quite like her nor have that kind of experience.  That's how I think of 10/10 anyway.  

I have met a provider to whom I gave that score.  I recently met another provider who I think deserves a 10 for appearance, but in a different way than that other provider.  Right now I'd give this recently-met provider a 9 for performance, but the line is trending up with every date so she may end up being another 10/10, if I decide to write a review someday.  She already has many 10/10s.

I've given two providers 10/10 scores. Both were as beautiful as any actress I've seen, and both were incredible performers, willing to do anything.

One of them recently gain a lot of weight. If I saw her again and did a review, I wouldn't be able to give her even an 8. In a few years, if both of them are still in the business, it's unlikely either will be 10/10's.  

One of the two has nothing but 10/10 scores. I know for a fact that she pressures those who give lower scores to raise them, and has less than 10/10 reviews removed.

...it is definitely possible for a low-volume lady to "legitimately" have nothing but 10/10s.

One of my favorite playmates has something like 20 reviews over the past three years--all 10/10s.  But she really is low-volume; she has civvie jobs in addition to her provider gigs, and will only see guys with whom she thinks there will be a "good connection".

She absolutely deserves those 10/10s--but in part, those stellar reviews come from her ability to be selective in her clientele.

there is a huge fiasco going on  in Vegas the past months with a group of ladies (commonly referred to on TER as "the Group")  
and they have shill reviews all 10/10
in fact the number 1 provider here recently is such a girl who has only been around since december.
Theres at least a dozen other ladies involved.

 
On the other hand . there is also the psychology of herd mentality
If a lady has a lot of 10/10 then following reviewers feel pressured to rate the same so as not to dilute her perfect score.

Its a flawed system IMHO