I  believe that some reviews are just mean. shouldn't the provider be able to rebuttal                         Just saying  

It has occurred to people apart from you that other humans aren't always completely honest

At least not by myself and not by a lot of other guys who post here.

I would add a third section to the review which would be titled, "Providers Comments".
After the review was posted, she would have a chance to give her comments or not provider her comments on the review.
She could say, " great time with a wonderful gentleman" or she could say, " no, he did not fuck me the ass bare back" or she could say nothing at all.
We are all (well most of us that stick around for any time) intelligent people who can read between the lines and decide for ourselves the probably truth of the matter.

I read them all, or at least recent ones.  Then take the average.

First, as others have said what lead you to believe reviews are taken as truth by any of us, much less most of us? As SH notes (based on the subj at least) I, and I suspect most hobbyists, read a number of the reviews, and all if there are not many that are dated. I also check the review pattern of the review's other reviews to form an opinion of the provider.

For other services allow a vendor to respond to a negative review.

Because I take all of the ones I read with a grain of salt.

At the suggestion that some reviews are not completely accurate.  Who would have ever guessed?

I checked the reviewer's history and checked their patterns. I learned to see the pattern of the providers and ignore the weird reviews that didn't fit.
As I gained experience and saw several providers, I checked the reviewers that had seen the ladies I had seen and had similar experiences. I started to trust their reviews of other providers and they were mostly similar to my experiences.
I really don't trust reviewers that have one or two reviews, whether they give a positive or negative review. It is quite a small world once I get to know who are fairly reliable reviewers and that their tastes are similar to mine.

except for all the others.

I would have a box for the lady to check or mark which one occurred or if the review is accurate.
Don't want to have a long he said/she said type of review or dialog
Here are my options, feel free to add one that could be better... no wise cracks here.
Accurate
Somewhat Accurate
Not exactly
Met but couldn't fuck
Never met

...if we can't trust mongers & pooners, well then who the hell can we trust?

At this point I believe more of the reviews are fabricated either in whole are part, than are factual.  

I have compiled a list over the years of reviewers who seem to like the same types of girls I like, so I give more weight to their reviews when researching new girls I'm thinking about seeing.  It has served me well for several years now.  

You can tell by the details in the review if he gave her a low score when she didn't deserve it. Also, it is important to see the reviewers reviews as some just can't handle giving anything above a 6. I have a few reviewers who rated me far above the next one, but still wasn't a 9 or a 10. Even if you are know to give great experiences, some won't give 7's or above because they are that picky or don't understand the rating system. I am sure some were bad but I know of at least one lady who, according to the details, was a 9 and he gave a 6.  

You have to look at a reviewer's entire history.  Many guys have never given a score above a 7 or 8, so for these guys, a score of 7 might be like my 9.  It relative to the range he uses overall.  Many guys think you can only give one 10 in your hobby career because they take the "Once in a Lifetime" description literally.

Now that is not going to happen. Because of the new scoring requirements there "might" be more objective numbers.
I'm trying to decide who I want to set up a MFM to score a provider a 10. Greek is way to easy, may as make it interesting.

not that easy if you're on the receiving end!!!