In addition to the current rating system, TER should have 1 question: please rate your overall satisfaction with the experience on a scale of 1-10.  Consider the following factors:

* Value
* Desire to exceed your expectations
* Quality of experience
* Screening and booking process
* Range of services offered

And perhaps 4-8 other factors.  Individuals should determine the trade space between factors and/or the relative importance of each factor.  That should augment the existing rating scheme.  Scores should be rolled up for agencies.  

... when deciding what Performance rating to give on a review.

A good review system will have some abstraction from the final score. The tendency for a 1-10 score to be polarized higher than it should be means that you're really not getting a good picture of actual performance. There's too much bias in just choosing a final, concrete score.

Here's the solution:  
In short, Itemized service reviews and aggregated total scores.    
   
For each of the services rendered, the provider gets a 1-10 score.  
This means that, if the provider performs DFK, BBBJ, CFS, they would get 3, 1-10 scores for their work.  
Then, the scores are averaged to determine the aggregate performance score.    
   
   -Performing more services would allow a provider to pad their scores with additional services only if the services provided were actually worthy of high scores.  
   -Performing a limited number of services would allow a provider to score higher only if said services were performed well, but would penalize a provider more if any of those services were performed poorly. It does not explicitly penalize providers for not performing certain services.  
   -Additional data capture would allow the search function to be more granular. Clients would be able to search for who was performing well at a particular service.  
   -Reviews would be more useful to providers because they would have granular feedback on which services they offer score highly and which services they could work on.